A mathematical model of wound healing and subsequent scarring

Wound healing is a complex process involving the delicate interaction between elements that vary widely in nature and size scales, from the nanometre level, such as molecules, to cells measured in micrometres, and fibres with width and length measured on both scales. Hybrid approaches, where each species is represented by a model on an appropriate size scale, have received attention recently. In this study, we provide a review of earlier work on such hybrid models of wound healing. General models for each of the element types involved in dermal wound healing used in this research are described: cells, modelled as discrete individuals; chemicals, modelled as continua; and fibres, modelled with a novel tensorial representation. Techniques for integrating such disparate models are outlined. A six-species model (fibrin, collagen, macrophages, fibroblasts, transforming growth factor-β (TGF-β) and tissue plasminogen activator) of dermal wound healing is presented. The role of the cytokine TGF-β in the healing cascade is investigated using the model, along with its role in the degree of scarring in the healed tissue.     

数控加工仿真中的优化离散矢量模型

数控加工仿真是利用计算机模拟数控加工的过程。采用离散知音一法可以有较好的实时性和观察性。但在采用离散矢量法时，离散模型的建立对仿真的效果有很大的影响。而对于常用的彩和均匀离散方式建立起来的仿真模型，对仿真精度与仿真速度的要求无法同时得到满足，本文采用了一种基于非均匀离散的优化模型可以有效地解决此点不足，并将详细论述这种仿真模型的建立、数据更新及其显示等内容。     

Pluronic lecithin organogel of 5-aminosalicylic acid for wound healing

5-Aminosalicylic acid (5-ASA) is an aminosalicylate anti-inflammatory drug, which is also known as mesalazine or mesalamine. Currently employed in treating inflammatory bowel disease, ulcerative colitis, inflamed anus or rectum, and maintain remission in Crohn's disease. Evidence from the researchers highlighted its significant re-epithelization in allergic asthma, aphthous, and gastric ulcerative conditions. The objective of the study was to formulate the pluronic lecithin organogel (PLO) containing 5-ASA and evaluate its wound-healing ability in a full thickness excision wound rat model. The data obtained from in silico docking studies revealed 5-ASA is having an affinity towards the transforming growth factor-beta (TGF-β) specifically towards beta1. Among various formulations prepared (F1 to F8), F1, and F6 have shown a maximum in vitro drug release with optimum pH and viscosity. From MTT assay it was found that selected PLO formulations showed no toxicity and enhanced cell proliferation in HaCaT cell lines. In vivo wound-healing studies in albino Wistar rats has revealed that PLO accelerates wound closure and reepithelization to the statistically significant level on day 3 (p?相似文献   

Aerosol-based efficient delivery of telithromycin,a ketolide antimicrobial agent,to lung epithelial lining fluid and alveolar macrophages for treatment of respiratory infections

Purpose: The efficacy of aerosol-based delivery of telithromycin (TEL), as a model antimicrobial agent, for the treatment of respiratory infections was evaluated by comparison with oral administration. Method: The aerosol formulation (0.2 mg/kg) was administered to rat lungs using a Liquid MicroSprayer®. Results and discussion: The time courses of the concentration of TEL in lung epithelial lining fluid (ELF) and alveolar macrophages (AMs) following administration of an aerosol formulation to rat lungs were markedly higher than that following the administration of an oral formulation (50 mg/kg). The time course of the concentrations of TEL in plasma following administration of the aerosol formulation was markedly lower than that in ELF and AMs. These results indicate that the aerosol formulation is more effective in delivering TEL to ELF and AMs, compared to the oral formulation, despite a low dose and it avoids distribution of TEL to the blood. In addition, the antibacterial effects of TEL in ELF and AMs following administration of the aerosol formulation were estimated by pharmacokinetics/pharmacodynamics analysis. The concentrations of TEL in ELF and the AMs time curve/minimum inhibitory concentration of TEL ratio were markedly higher than the effective values. Conclusion: This study indicates that an antibiotic aerosol formulation may be an effective pulmonary drug delivery system for the treatment of respiratory infections.     

自动化集装箱码头运输系统配置的仿真优化

以新型自动化集装箱码头中间运输系统为研究对象,建立了自动化集装箱码头中间运输系统的仿真优化模型,并利用仿真优化方法搜索优化调度方案,最小化船舶靠岸后装卸作业的总时间和最大化各种设备的操作效率,优化模块使用遗传算法,整个程序使用C#语言编制.通过仿真计算表明能够非枚举地从所有可能的动态调度方案中搜到最佳方案:运输系统的设备利用率、系统作业时间,都得到了相应改善.     

水平圆筒型混合机中颗粒混合的离散模拟

采用离散模型模拟了水平圆筒型混合机中 10 0 0个颗粒混合的全过程 ,分析了颗粒流型的变化规律和混合曲线 ,得到了颗粒由相对静止到开始下滑的塌落过程 ,所得结果与已知实验结果符合很好 ,这有助于揭示混合机内部颗粒的运动规律     

Simulation of capacity and cost for the planning of future process chains

One of the most promising approaches in modern microelectronics is the introduction of 3D chip micro systems with through-silicon via (TSV) interconnections. A successful transfer of this technology from the scientific level up to the level of mass production is not least of all a matter of cost-effectiveness and profit, which is directly related to high productivity. The developed technologies therefore have to be feasible for effective mass production. In this paper we introduce a method for planning and evaluating costs in future process chains. This method goes beyond usual mostly Excel-supported solutions, as it is based on a discrete event simulation system. The simulation model is generically generated out of an XML process chain definition file and includes a sophisticated state model for machines. Multiple process scenarios are created with the help of a supporting software tool. These scenarios are investigated for achieving favourable equipment and process chain configurations as well as control strategies to support manufacturing ramp-ups.     

DFT的装配车间生产物流策略仿真与研究

针对某汽车部件的实际装配生产,运用离散事件仿真的方法对基于需求流动技术(DFT)的装配生产物流策略进行了研究.在分析该汽车部件装配生产流程的基础上,确定eM-Plant仿真软件中的建模对象与装配生产系统中实体对象的对应关系,使用面向对象的方法建立了相应的离散事件仿真模型.在模型中分别实施基于推式生产方式的物流策略和基于DFT的物流策略,以该汽车部件的平均日产量为绩效指标,比较了两种物流策略对装配生产的影响.     

时效组织演化的计算机模拟理论与模型

总结了时效组织的计算机模拟研究,基于Cahm-Hillard的非经典转变理论,提出一种新的动力学模型,不同于以往的连续介质模型,为离散格点形式,可租用于时效过程的所有阶段,包括形核、长大、粗化等,模型还可描述原子有序化和相分离,并考虑到弹性能对形貌演化和粗化过程的影响,且体积分数的影响、沉淀颗粒间的相互作用也在方程中自动体现。     

Preparation,characterization, and in vivo evaluation of nano formulations of ferulic acid in diabetic wound healing

Diabetes mellitus is most common disorder characterize by hyperglycemia. Chronic hyperglycemia may lead to over production of free radicals thereby results in oxidative stress which impaired healing of wounds. Ferulic acid (FA) has been shown to have antidiabetic and antioxidant properties. The aim of the present study was to develop Ferulic acid nanoparticles and to study its hypoglycemic and wound healing activities. Ferulic acid-poly(lactic-co-glycolic acid) (FA-PLGA) nanoparticles were prepared by nano precipitation method. The prepared FA-PLGA nanoparticles had an average size of 240?nm. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) analysis showed the prepared FA-PLGA nanoparticles were spherical in shape. Drug encapsulation assay showed that 88.49% FA was encapsulated in PLGA. Carbopol 980 was used to formulate FA-PLGA nanoparticles loaded hydrogel. FA-loaded polymeric nanoparticles dispersion (oral administration) and FA-loaded polymeric nanoparticles based hydrogel (topical administration) treated wounds were found to epithelize faster as compared with diabetic wound control group. The hydroxyproline content increased significantly when compared with diabetic wound control. Therefore, the results indicate that FA significantly promotes wound healing in diabetic rats.     

回转窑内颗粒轴向混合运动的数值模拟

为了研究不同粒径颗粒在水平回转窑内轴向混合运动机理,采用离散元软件EDEM对窑内颗粒轴向混合过程进行数值模拟,引入颗粒接触数动态跟踪颗粒的混合过程,以大、小颗粒接触数来衡量颗粒间的混合程度。结果表明:活动层内颗粒的运动速度较大;小颗粒轴向运动的主要方式是透过大颗粒间的间隙向大颗粒群渗透。     

机械应力刺激对体外肺腺癌细胞增殖的影响

通过FX-4000柔性基底加载系统研究了不同波形的周期性拉伸对人肺腺癌A549细胞株增殖的影响,应用Image—pro图像处理软件对A549细胞株在心形波、三角波及方波等拉伸应变下的增殖动力学变化进行了分析。实验结果表明：在collagenⅠ基底膜上,应变为0％～20％,频率为0．5Hz及1．0Hz,加载时间为2h时,与对照组比较,方波刺激组细胞生长明显受到抑制,三角波与心形波刺激组细胞增殖率无明显差异。研究表明：A549细胞株对体外的生理应变作出响应时,方波的抑制作用最佳,而拉伸频率的影响并不明显。     

A model based approach to assess the performance of production systems in degraded mode

Nowadays production systems are asked to perform their activities in a high uncertainty environment and to guarantee their performance in this environment. Therefore, they are asked to master risks that are part of their daily activities, to maintain the performance which is considered as their key success factor. Risks may cause serious effects that threaten the production systems and degrade their performance. Nevertheless, we cannot estimate the degradation that a risk may cause to system performance, since risk analysis methods found in the literature do not allow simulating the behaviour of the system in degraded mode. In order to help production systems to assess their performance in risk situations, we propose in this paper a model-based approach that enables assessing the performance of production systems in degraded mode. Our approach is based on function, interaction, structure (FIS) modelling framework that enables modelling complex system and its failures. The resulting model is converted into an executable simulation model based on a new class of Petri Nets (PNs) called predicate-transition, prioritised, synchronous (PTPS) PN. The obtained simulation model is then executed in order to obtain performance indicators in degraded mode. This tool is used during the system design, in order to study the impact of risks on the designed production system performance. It is also used to study an existing production system in order to analyse and optimise its behaviour in degraded mode. In this article, we present our tool and apply it to a special case of production systems which is a hospital sterilisation system.     

人-飞机-环境系统模拟中数学模型的研究与分析

通过对人－飞－环境模拟仿真技术中人操作的数学模型及“人－飞机－环境”操纵系统的数学模型的研究,具体分析了人的传递函数模型,最佳控制模型,模糊控制模型的适应范围及优缺点,并在对、人－飞机－环境”操纵系统的数学模型,性能指标进行分析后,提出了确定驾驶员和飞机之间最佳匹配的“人－飞机－环境”操纵系统计算机模拟综合评估系统,从而使人们一开始设计飞机时就考虑驾驶员作用,养活主设计盲目性,缩短设计周期,尤其在目前,先进技术的广泛应用使 飞机出现一些非常常规的运动,故更需进行人－机闭环综合分析,才能到做各系统功能合理分配,充分发挥飞机的整体效能。     

对撞超声速射流场的数值模拟研究

为了探讨对撞式气流粉碎机内部的对撞超声速射流流场结构对粉碎过程的影响,本文中通过数值模拟的方法,对该流场结构进行了研究。通过建立不同的模型,对射流出口与对称平面的距离对粉碎过程的影响,以及射流外围的流动情况进行了分析,为高效气流粉碎机的设计提供了参考依据。     

装饰建材超市气流组织的数值模拟

本文介绍了装饰建材超市气流组织紊流数值模拟的方法,讨论了应用最为广泛的高雷诺数模型及其数值计算方法,并提出了气流组织数值模拟中有待解决的问题.     

RFI成型工艺的数值模拟研究进展

综述了树脂膜熔渗(RFI)成型工艺数值模拟所依赖的数学模型以及核心算法的研究进展,着重总结了树脂的流动、抑制孔隙产生、热传递以及固化动力学等方面数学模型的研究进展.对这些模型的研究有利于更加深入地理解成型工艺中复杂的物理和化学变化,通过数值模拟可以预测工艺参数,从而优化整个工艺过程、缩短研发周期.     

焊接熔池组织模拟的GBE模型

介绍了焊接熔池组织模拟的GBE模型。此模型是通过计算相邻晶粒间晶界的位置变化来模拟晶粒的生长,为焊接熔池组织的模拟提供了新思路。重点介绍了模型假设和模型的实现,并对此模型进行了评述,提出了模型的发展方向。     

Development and in vitro/in vivo evaluation of HPMC/chitosan gel containing simvastatin loaded self-assembled nanomicelles as a potent wound healing agent

The aim of this study was to develop hydroxypropyl methyl cellulose (HPMC)/chitosan gel containing polymeric micelles loaded with simvastatin (Sim) and evaluates its wound healing properties in rats. An irregular full factorial design was employed to evaluate the effects of various formulation variables including polymer/drug ratio, hydration temperature, hydration time, and organic solvent type on the physicochemical characteristics of pluronic F127-cholesterol nanomicelles prepared using the film hydration method. Among single studied factors, solvent type had the most impact on the amount of drug loading and zeta potential. Particle size and release efficiency was more affected by hydration temperature. The optimized formulation suggested by desirability of 93.5% was prepared using 1?mg of Sim, 10?mg of copolymer, dichloromethane as the organic solvent, hydration time of 45?min and hydration temperature of 25?°C. The release of the drug from nanomicelles was found to be biphasic and showed a rapid release in the first stage followed by a sustained release for 96?h. The gel-contained nanomicelles exhibited pseudo-plastic flow and more sustained drug release profile compared to nanomicelles. In excision wound model on normal rats, the wound closure of the group treated by Sim loaded micelles-gel was superior to other groups. Taken together, Sim loaded micelles-gel may represent a novel topical formulation for wound healing.     

核电站穹顶内热环境的数值模拟

以CPR1000核电站R55区穹顶为研究对象,基于计算流体力学(CFD)技术,应用P-1辐射模型对穹顶内部温度场进行了3D稳态数值模拟与实验验证。结果表明:6月26日6个时刻,空穹顶内Z=11m处的温度模拟值与实测值吻合良好,最大相对误差为3.23%,平均相对误差为1.05%;9:00穹顶内垂直方向温度分布梯度明显,最大温差达到6℃。P-1辐射模型模拟太阳辐射对核电站穹顶内热环境的影响是可行的。