Numerical Study of the Biomechanical Behavior of a 3D Printed Polymer Esophageal Stent in the Esophagus by BP Neural Network Algorithm

Esophageal disease is a common disorder of the digestive system that can severely affect the quality of life andprognosis of patients. Esophageal stenting is an effective treatment that has been widely used in clinical practice.However, esophageal stents of different types and parameters have varying adaptability and effectiveness forpatients, and they need to be individually selected according to the patient’s specific situation. The purposeof this study was to provide a reference for clinical doctors to choose suitable esophageal stents. We used 3Dprinting technology to fabricate esophageal stents with different ratios of thermoplastic polyurethane (TPU)/(Poly-ε-caprolactone) PCL polymer, and established an artificial neural network model that could predict the radial forceof esophageal stents based on the content of TPU, PCL and print parameter. We selected three optimal ratios formechanical performance tests and evaluated the biomechanical effects of different ratios of stents on esophagealimplantation, swallowing, and stent migration processes through finite element numerical simulation and in vitrosimulation tests. The results showed that different ratios of polymer stents had different mechanical properties,affecting the effectiveness of stent expansion treatment and the possibility of postoperative complications of stentimplantation.

A novel nano-grade organosilicon polymer:Improving airtightness of compressed air energy storage in hard rock formations

Enhancing cavern sealing is crucial for improving the efficiency of compressed air energy storage(CAES)in hard rock formations.This study introduced a novel approach using a nano-grade organosilicon polymer(NOSP)as a sealant,coupled with an air seepage evaluation model that incorporates Knudsen diffusion.Moreover,the initial coating application methods were outlined,and the advantages of using NOSP compared to other sealing materials,particularly regarding cost and construction techniques,were also examined and discussed.Experimental results indicated a significant reduction in permeability of rock specimens coated with a 7–10μm thick NOSP layer.Specifically,under a 0.5 MPa pulse pressure,the permeability decreased to less than 1 n D,and under a 4 MPa pulse pressure,it ranged between4.5×10^(-6)–5.5×10^(-6)m D,marking a 75%–80%decrease in granite permeability.The sealing efficacy of NOSP surpasses concrete and is comparable to rubber materials.The optimal viscosity for application lies between 95 and 105 KU,and the coating thickness should ideally range from 7 to 10μm,applied to substrates with less than 3%porosity.This study provides new insights into air transport and sealing mechanisms at the pore level,proposing NOSP as a cost-effective and simplified solution for CAES applications.

Species distribution of polymeric aluminium ferrum——timed complexation colorimetric analysis method of Al-Fe-Ferron

The effects of the calorimetric buffer solutions were investigated while the two colorimetric reactions of AI-ferron complex and Fe-ferron complex occurred individually, and the effects of the testing wavelength and the pH of the solutions were also investigated. A timed complexatian colorimetric analysis method of Al-Fe-ferron in view of the total concentration of {AI + Fe} was then established to determine the species distribution of polymeric Al-Fe. The testing wavelength was recommended at 362 net and the testing pH value was 5. With a comparison of the ratios of n(Al)/n(Fe), the standard adsorption curves of the polymeric Al-Fe solutions were derived from the experimental results. Furthermore, the solutions' composition were carious in both the molar n(Al)/n(Fe) ratios, i.e. 0/0, 5/5, 9/1 and 0/10, and the concentrations associated with the total ( Al + Fe which ranged from 10(-5) to 10(-4) mol/L..

Study of the Conductance Characteristic of Doped Polymer by Monte Carlo Method

The conduct mechanism of the doped polymer is considered. In an asymmetrysystem composed of high polymer and doping conductive matte, chain or congeries framework will beformed between the conductive particles to improve the conductance characteristic. In thisprocession, the conductive particles interact to each other. In this paper, we describe theconductance of the doped polymer by Monte Carlo method. The results accord with the experimentsquite well. It can be concluded that there is an evident change of doped polymer from nonconductorto metal.

Species analysis methods for hydrolysis polymerization of aluminum

Al Ferron timed complex colorimetric method (AFM) and 27 Al NMR spectroscopy method(ANM) were discussed. For the former, the different colorimetric reagent preparation methods' results indicate that there are some differences beteween them, and the combined method can be used as a simplified procedure. For the latter, the small tube method is more accurate. Eventually, the Al 13 (ANM) was compared to the Al b (AFM).

Template Polymerization Based on Stober Method:an Improved Method for Fabrication of Hollow Polysiloxane Spheres

A modified Stober method has been developed which permits the controlled growth of spherical hollow spheres with diameters between 197 and 208 nanometers by consecutively cocondensed methyltrimethoxysilane and dimethyldimethoxysilane monomers onto microemulsion of polydimethylsiloxane and subsequently removing the templated polydimethylsiloxane by exposure to solvents. Ammonia was used as a morphological catalyst. The morphology of the polymer spheres was demonstrated by transmission electron micrographs （TEM） and atomic force microscopy （AFM）.

Ultravilolet-radiation-induced graft polymerization of acrylamide onto the melt-blown polypropylene filter element by dynamic method

By dynamic method under UV irradiation, commercial melt-blown polypropylene （PPMB） filter element was modified with acrylamide （AAm） using benzophenone （BP） as initiator. Attenuated total reflection-Fourier transform infrared spectroscopy and scanning electron microscope verified that polyacrylamide chain was grafted on the fiber surface of PPMB filter element. Elemental content analysis with energy dispersive X-ray of fibers revealed that the polymerization content in the inner part of filter element was relatively higher than that in the outer. Degree of grafting changed with initiator concentration, monomer concentration, reaction temperature and reached 2.6% at the reaction condition： CBp=0.06 mol/L, CAAm=2.0 mol/L, irradiation time： 80 min, temperature： 60℃. Relative water flux altered with the hydrophilicity and pore size of filter element. In the antifouling test, the modified filter gave greater flux recovery （approximately 70%） after filtration of the water extract of Liuweidihuang, suggesting that the fouling layer was more easily reversible due to the hydrophilic nature of the modified filter.

Measurement Method of the Thickness Uniformity for Polymer Films

Several methods for investigating the thickness uniformity of polymer thin films are presented as well as their measurement principles. A comparison of these experimental methods is given.The cylindrical lightwave reflection method is found to can obtain the thickness distribution along a certain direction.It is a simple and suitable method to evaluate the film thickness uniformity.

Finite element method for coupled diffusion-deformation theory in polymeric gel based on slip-link model

A polymeric gel is an aggregate of polymers and solvent molecules, which can retain its shape after a large deformation. The deformation behavior of polymeric gels was often described based on the Flory-Rehner free energy function without considering the influence of chain entanglements on the mechanical behavior of gels. In this paper,a new hybrid free energy function for gels is formulated by combining the EdwardsVilgis slip-link model and the Flory-Huggins mixing model to quantify the time-dependent concurrent process of large deformation and mass transport. The finite element method is developed to analyze examples of swelling-induced deformation. Simulation results are compared with available experimental data and show good agreement. The influence of entanglements on the time-dependent deformation behavior of gels is also demonstrated.The study of large deformation kinetics of polymeric gel is useful for diverse applications.

EFFECTS OF REACTION AND PROCESSING PARAMETERS ON ETHYLENE POLYMERIZATION USING DIFFERENT ZIEGLER-NATTA CATALYSTS:EMPLOYMENT OF TAGUCHI EXPERIMENTAL DESIGN AND RESPONSE SURFACE METHOD

Different Ziegler-Natta catalysts were employed to polymerize ethylene. To investigate the influences of reaction parameters, namely Al/Ti molar ratio, hydrogen and processing parameters, i.e. ethylene pressure and temperature, a Taguchi experimental design was worked out. An L27 orthogonal array was chosen to take the above-mentioned parameters and relevant interactions into account. Response surface method was the tool used to analyze the experimental design results. Al/Ti, ethylene pressure and temperature were selected as experimental design factors, and catalyst activity and polymerization yield were the response parameters. Increasing pressure, due to an increment in monomer accessibility, and rising Al/Ti, because of higher reduction in the catalysts, cause an increase in both polymerization yield and catalyst activity. Nonetheless, a higher temperature, thanks to reducing ethylene solubility in the slurry medium and partially catalyst destruction, lead to a reduction in both response parameters. A synergistic effect was also observed between temperature and pressure. All catalyst activities will reduce in the presence of hydrogen. Molecular weight also shows a decline in the presence of hydrogen as a transfer agent. However, the polydispersity index remains approximately intact. Using SEM, various morphologies, owing to different catalyst morphologies, were seen for the polyethylene.

Regioselectivity Study on Propylene Polymerization Catalyzed by Neutral Salicyladiminato Pd(II) Model Complex with DFT Method

Many attempts have been made to control the regioselectivity for olefin poly- merization by varying the structures of ligands in catalysts. The regioselectivity of propylene polymerization was investigated by replacing a nitrogen atom in the Pd(II) diimine catalyst with an oxygen atom from density functional theory method at the B3LYP/LANL2DZ level. The results show that the 1,2-insertion becomes a rival mechanism to the 2,1-insertion when the nitrogen atom is replaced by the oxygen atom leading to an asymmetric environment in the catalyst, and that the steric effect in the asymmetrical catalyst plays an important part in the polymerization. The insertion barrier from 2-O is much higher than that from 2-N. A pyramid transition state was characterized for the catalyst to convert 2-O back to 2-N through internal rotation. The propylene prefers to coordinate at the opposite side of O in the catalyst. This is the driving force for the internal rotation. The results are significant for isotactic and syndiotactic polymerization.

Effect of Main Material Ratio on Properties of SiC-Al_2O_3 Porous Ceramics via Polymeric Replication Method

In order to fabricate porous ceramics with good properties and proper production cost,SiC-Al2 O3 porous ceramics were prepared at 1 450 ℃ for 2 h from the powders of commercial silicon carbide and white fused corundum via a polymeric replication method. Effects of the mass ratio of SiC powder to white fused corundum powder（ 1 ∶ 3,1 ∶ 1 and 3 ∶ 1） on the appearance,phase composition,sintering properties and thermal shock resistance were investigated. The research results indicate that the as-prepared Si C-Al2 O3 porous ceramics have uniform pores,and their linear shrinkage ratio,apparent porosity and bulk density reach 4. 70%,67. 17%and 0. 83 g·cm-3,respectively. The thermal shock cycles from 1 400 ℃ to room temperature reach 23 including 15 cycles in air cooling condition and then 8 cycles in water cooling condition. Their main phases areα-Al2 O3 and Al6 Si2 O13 as well as a small amount of SiC and free SiO2. The as-prepared porous ceramic with the ratio of m（ SiC） ∶ m（ Al2 O3） = 1∶ 1 possesses prior comprehensive properties.

AN EXTENSION OF THE METHOD FOR PREDICTING PERMEABILITY THROUGH POLYMER MEMBRANES FROM SIMPLE GASES TO WATER VAPOR

It is found that there is a linear relationship between log P-w, and the parameter term V-f/0.5 E(coh) [1+(delta(w) - delta(p))(2)/delta(p)(2), from the water permeability (P-w) data of 21 polymers covering 4 orders of magnitude. This correlation may be useful in choosing membrane materials for dehumidification of gases.

A NOVEL POLYMER ENZYME LINKED IMMUNOASSAY METHOD AND ITS APPLICATIONS

During the course of study, we found that both poly (N-isopropylacrylamide ) (PNIP) and PNIP-Ab (enzyme-labelled antibody)could be adhere tightly to a cellulose acetale-nitrate membrane, and that the retention of PNIP-Ab on the membrane increased over 30-fold when compared with the unconjugated Ab.Thus we used this characteristic to develop a novel immunoassay method-polymer enzyme linked immunoassay method: homogeneous antigen-antibody reaction and heterogeneous separation process. When applied for detection of human serum HBsAg, this immunoassay system can detect as little as 1 ng/ml of human serum HBsAg.

Development of Green Polymer Electrolyte Through Hot Press Method

To develop the green polymeric membrane electrolyte,-Polycaprolactone(PCL)was used as a host and the Ionic liquid(IL)(1-Ethyl-3-methylimidazolium tosylate)as a dopant.The IL is a source of mobile charges in the polymer electrolyte system.The composite membrane has been prepared by Hot Press method and then we characterised this membrane for ionic transportation.Formation of nanocomposite system has been ascertained from their XRD pattern.Interaction phenomenon was studied by ATR based FTIR and Laser Raman spectroscopic technique.Variation of conductivity with composition and temperature was studied with the aid of impedance spectroscopy data.

Morphological and Electrochemical Characterization of Ti/MxTiySnzO2 (M = Ir or Ru) Electrodes Prepared by the Polymeric Precursor Method

This paper describes the effect of the composition of the oxide films on the properties of electrodes Ti/MxTiySnzO2 (M = Ir or Ru) prepared by the polymeric precursor method. XRD studies showed that the anodes are formed by solid solutions. The electrodes containing IrO2 exhibit lower activity for the oxygen evolution reaction. The doping of the electrode surface with SnO2 improves the catalytic properties of the anodes. However, it should be held in appropriate compositions, because the change in the atomic ratio of this element shows a marked effect on the stability of the oxides. Electrode Ti/Ir0.2Ti0.3Sn0.5O2 has lower lifetime, i.e. 6 hours. The 20% decrease in the stoichiometric amount of SnO2 increases the time to a value above 70 hours, as observed for Ti/Ir0.3Ti0.4Sn0.3O2. Electrode Ti/Ru0.3Ti0.4Sn0.3O2 shows lifetime of 11 hours;therefore IrO2 is more stable than RuO2 under the conditions investigated. These results suggest that electrode Ti/Ir0.3Ti0.4Sn0.3O2 is promising for different applications, such as water electrolysis, capacitors and organic electrosynthesis.

Use of Perovskite-Type Lanthanum Nickelate Synthesized by the Polymeric Precursor Method in the Steam Reforming Reaction of Methane

In the current work, LaNiO3 perovskite was synthesized using the polymeric precursor method. The materials were thermally treated at 300°C for 2 hours, subsequently supported on alumina or zirconia and finally calcined at 800°C for 4 hours. The resulting samples were characterized by X-ray diffraction, thermogravimetry, BET surface area and thermo-programmed reduction. Steam reforming reactions were carried out at 750°C and 6 bar during 4 hours using a pilot reactor under a H2O:CH4 ratio of 2.5. The mass of catalysts was about 5.7 g. X-ray diffraction patterns confirmed the formation of the perovskite structure in all samples prepared. The results also showed that lanthanum nickelate was more efficient when supported on alumina than zirconia. Finally, it was observed that the methane conversion was approximately 94% and the selectivity to hydrogen was about 70%. In all cases low selectivity to CO and CO2 was verified.

Research on the Teaching Reform of Polymer Materials Foundation Course-Based on the Case Analysis Method

In today's education and teaching reform,the traditional teaching method in the teaching of polymer materials has been gradually replaced with various new teaching methods.Among them,the case analysis method is a very efective teaching method,which has been applied to the teaching of polymer materials.Through example-based teaching,students 125 participation can be effectively improved,and their theoretical knowledge can be fully utilized.This would have a positive role in promoting the improvement of students'knowledge system and their learning ability.In regard to this,this article analyzes the application of case analysis in the teaching of polymer materials so as to improve its efficiency and quality.

纳米富锂锰基正极材料的合成及性能研究

富锂层状氧化物材料具有较高的比容量,被认为是下一代先进锂离子电池正极材料。采用丙烯酸热聚合法和柠檬酸溶胶-凝胶法分别合成了纳米富锂锰基正极材料Li_(1.2)Mn_(0.54)Ni_(0.13)Co_(0.13)O_(2),并进行Mg^(^(2+))掺杂改性。通过扫描电子显微镜、X射线粉末衍射仪对制备的正极材料进行形貌和结构表征,并组装成纽扣电池进行充放电性能测试和电化学阻抗谱分析。结果表明,丙烯酸热聚合法合成的正极材料粒径均匀,结晶度更高;与未掺杂样品相比,掺杂Mg^(2+)的正极材料首次库伦效率从67.66%提高到73.34%,循环性能显著改善。

A Modified Phase-Field Model for Polymer Crystal Growth

The irrationality of existing phase field model is analyzed and a modified phase-field model is proposed for polymer crystal growth, in which the parameters are obtained from real materials and very simple to use, and most importantly, no paradoxical parameters appeared in the model. Moreover, it can simulate different microstructure patterns owing to the use of a new different free energy function for the simulation of morphologies of polymer. The new free energy function considers both the cases of T〈Tm and T≥Tm, which is more reasonable than that in published literatures that all ignored the T≥Tm case. In order to show the validity of the modified model, the finite difference method is used to solve the model and different crystallization morphologies during the solidification process of isotactic polystyrene are obtained under different conditions. Numerical results show that the growth rate of the initial secondary arms is obviously increased as the anisotropy strength increases. But the anisotropy strength seems to have no apparent effect on the global growth rate. The whole growth process of the dendrite depends mainly upon the latent heat and the latent heat has a direct effect on the tip radius and tip velocity of side branches.