抗生素骨水泥填充技术联合自体富血小板血浆对慢性创面修复效果及病人生活质量的影响

目的探讨抗生素骨水泥填充技术(Masquelet)联合自体富血小板血浆(PRP)对慢性创面修复效果及病人生活质量影响。方法选择2018年1月至2018年10月安康市中医医院创伤整形科收治的慢性创面病人60例,按照治疗方法不同分为观察组30例及对照组30例;对照组病人创面清创后以PRP外敷治疗,观察组病人创面清创后先行Masquelet技术,后行PRP治疗。比较两组慢性创面病理切片中真皮细胞DNA含量、创面缩小率、细菌清除率、肉芽组织覆盖率、肉芽组织厚度以及治疗后生活质量(SF-36)评分。结果治疗后,观察组的创面病理切片中真皮细胞DNA含量为(27.56±1.23),明显多于对照组(24.26±0.53),P<0.05;观察组创面缩小率明显大于对照组[(82.25±9.68)%比(55.58±7.53)%,t=12.01,P<0.01];观察组细菌清除率明显高于对照组[(86.23±8.58)%比(76.01±7.56)%,t=11.24,P<0.01];观察组肉芽组织覆盖率明显高于对照组[(88.56±9.78)%比(66.58±6.54)%,t=10.33,P<0.01];观察组肉芽组织生长厚度明显厚于对照组[(6.58±0.21)mm比(4.19±0.37)%,t=19.26,P<0.01];治疗3个月后观察组SF-36评分高于对照组[(81.20±4.01)分比(71.50±5.19)%,t=5.66,P<0.01]。结论Masquelet技术联合PRP治疗慢性创面,可促进创面愈合,改善病人生活质量,可临床推广。

周期复合材料结构高阶多尺度方法的数值精度提高策略

高阶多尺度方法在计算数学、计算力学和计算材料学等领域得到了广泛的应用,为了进一步挖掘高阶多尺度方法的计算潜力,本文结合单胞边界条件优化选择和边界层构造,提出了一种高阶多尺度方法的数值精度提高策略,并给出了施加数值精度提高策略的高阶多尺度方法的误差分析.然后,建立了周期复合材料结构弹性力学问题具有数值精度提高策略的新的多尺度数值算法.最后,通过对周期复合材料结构弹性力学问题的模拟,验证了所提出数值精度提高策略的有效性和最优的数值精度.

基于分子动力学模拟的金属构件的弹-塑性分解方法

针对金属多晶材料构件的分子动力学(MD)模拟,本文提出了一种新的弹-塑性分解方法.文章将MD运动轨迹分解为结构变形和热振动,给出了计算结构变形的方法和近似公式;针对金属多晶材料构件的当前构型,给出了基于FCC|BCC晶胞和四原子占位的四面体单元相组合的连续变形函数及计算变形梯度的算法;利用原子-连续关联模型,发展了计算当前构型应力场和弹性张量的算法.分析了当构件承受过大载荷后在材料内部所产生的微观缺陷,并将其分类标定为位错、层错、挛晶界、晶界和空位等;对于层错和挛晶界讨论了在弹性卸载过程中应满足的刚体运动约束方程;利用极小势能原理构造了基于当前构型的弹性卸载算法,进而给出了完整的基于MD模拟的计算弹-塑性应变的算法.最后,针对单晶铜纳米线拉伸的MD模拟,计算了弹-塑性应变场,验证了本文方法的合理性.本文提出的基于MD模拟的弹-塑性分解方法,为从微观到宏观的多尺度和多模型耦合计算提供了算法支撑.

Atom-continuum coupled model for thermo-mechanical behavior of materials in micro-nano scales

In this paper,an atom-continuum coupled model for thermo-mechanical behaviors in micro-nano scales is presented.A representative volume element consisting of atom clusters is used to represent the microstructure of materials.The atom motions in the RVE are divided into two phases,structural deformations and thermal vibrations.For the structural deformations,nonlinear and nonlocal deformation at atomic scales is considered.The atomistic-continuum equations are constructed based on momentum and energy conservation law.The non-locality and nonlinearity of atomistic interactions are built into the thermo-mechanical constitutive equations.The coupled atomistic-continuum thermal-mechanical simulation process is also suggested in this work.

Interior Hlder and gradient estimates for the homogenization of the linear elliptic equations

H61der and gradient estimates for the correctors in the homogenization are presented based on the translation invariance and Li-Vogelius＇s gradient estimate. If the coefficients are piecewise smooth and the homogenized solution is smooth enough, the interior error of the first-order expansion is O（e） in the HSlder norm; it is O（e） in W1,∞ based on the Avellaneda-Lin＇s gradient estimate when the coefficients are Lipschitz continuous. These estimates can be partly extended to the nonlinear parabolic equations.

Second-order two-scale method for bending behavior analysis of composite plate with 3-D periodic configuration and its approximation

This paper considers the bending behaviors of composite plate with 3-D periodic configuration.A second-order two-scale(SOTS)computational method is designed by means of construction way.First,by 3-D elastic composite plate model,the cell functions which are defined on the reference cell are constructed.Then the effective homogenization parameters of composites are calculated,and the homogenized plate problem on original domain is defined.Based on the Reissner-Mindlin deformation pattern,the homogenization solution is obtained.And then the SOTS’s approximate solution is obtained by the cell functions and the homogenization solution.Second,the approximation of the SOTS’s solution in energy norm is analyzed and the residual of SOTS’s solution for 3-D original in the pointwise sense is investigated.Finally,the procedure of SOTS’s method is given.A set of numerical results are demonstrated for predicting the effective parameters and the displacement and strains of composite plate.It shows that SOTS’s method can capture the 3-D local behaviors caused by3-D micro-structures well.

A new method for modeling thermo-mechanical behaviors of polycrystalline aggregates

We present in this paper a numerical algorithm that couples the atomistic and continuum models for the thermal-mechanical coupled problem of polycrystalline aggregates.The key point is that the conservation laws should be satisfied for both the atomistic and continuum models at the microscale.Compared with the traditional methods which construct the constitutive equations of the grain interiors and grain boundaries by continuum mechanics,our model calculates the continuum fluxes through molecular dynamics simulations,provided that the atomistic simulations are consistent with the local microstate of the system.For the grain interiors without defects,central schemes are available for solving the conservation laws and the constitutive parameters can be obtained via molecular dynamics simulations.For the grain boundary structures,the front tracking method is employed because the solutions of the conservation equations are discontinuous near the defects.Firstly,appropriate control volumes are chosen at both sides of the interface,then the finite volume method is applied to solve the continuum equations in each control volume.Fluxes near both sides of the interface are calculated via atomistic simulations.Therefore,all thermo-mechanical information can be obtained.