随机有限元在采矿工程中的应用

采矿工程中存在很多的随机性因素,这关系到矿柱的可靠度.依靠传统的安全系数法不能考虑矿柱载荷和物理力学特性的随机性,因而具有很大的误差和局限性.本文介绍的随机有限元法将随机理论与有限元相结合,充分考虑了矿柱载荷的随机性和弹性模量的随机性,使矿柱可靠度的计算更符合实际.     

可注射性骨组织工程材料不饱和聚磷酸酯的交联特性

合成了主链重复结构单元中含不饱和双键的聚磷酸酯,利用FT-IR及NM R对其进行了表征。研究了聚合物分子量、交联剂N-乙烯基吡咯烷酮与引发剂过氧化苯甲酰的含量对最高交联温度、固化时间、压缩强度及压缩模量的影响。研究表明,体系的最高交联温度在41.1℃~82.3℃,低于骨修复材料甲基丙烯酸甲酯的最高交联温度97℃。引发剂含量的增加能够加快体系交联固化。提高分子量以及交联剂与引发剂的含量都能增加交联产物的压缩强度及压缩模量,四种配方所得交联产物的压缩强度为3.3M Pa~11.0 M Pa,压缩模量为4.9 M Pa~101.9 M Pa,接近松质骨的水平。因此,U PPE有可能成为一类新型的可注射性骨组织工程支架材料。     

强激光辐照下生物组织的瞬态温度场研究

研究生物组织在强激光作用下的瞬态温度分布,探讨强激光作用下生物组织的热传输规律,采用数值方法中的有限差分法求解热传导方程,得出了生物组织纵切面上温度的时空分布图、生物组织轴向温度按指数规律降低及径向上温度按偶次方幂函数规律变化,根据纵切面上温度时空分布图估算出热损伤深度,当激光功率密度分别为175W／cm^2和298W／cm^2时,热损伤深度分别为0．28mm和0．24mm,其值与相关实验值较好地符合。     

Adipose Stromal/Stem Cell-Derived Extracellular Vesicles: Potential Next-Generation Anti-Obesity Agents

Over the last decade, several compounds have been identified for the treatment of obesity. However, due to the complexity of the disease, many pharmacological interventions have raised concerns about their efficacy and safety. Therefore, it is important to discover new factors involved in the induction/progression of obesity. Adipose stromal/stem cells (ASCs), which are mostly isolated from subcutaneous adipose tissue, are the primary cells contributing to the expansion of fat mass. Like other cells, ASCs release nanoparticles known as extracellular vesicles (EVs), which are being actively studied for their potential applications in a variety of diseases. Here, we focused on the importance of the contribution of ASC-derived EVs in the regulation of metabolic processes. In addition, we outlined the advantages/disadvantages of the use of EVs as potential next-generation anti-obesity agents.     

Validation of a Cleanroom Compliant Sonication-Based Decellularization Technique: A New Concept in Nerve Allograft Production

Defects of the peripheral nervous system are extremely frequent in trauma and surgeries and have high socioeconomic costs. If the direct suture of a lesion is not possible, i.e., nerve gap > 2 cm, it is necessary to use grafts. While the gold standard is the autograft, it has disadvantages related to its harvesting, with an inevitable functional deficit and further morbidity. An alternative to autografting is represented by the acellular nerve allograft (ANA), which avoids disadvantages of autograft harvesting and fresh allograft rejection. In this research, the authors intend to transfer to human nerves a novel technique, previously implemented in animal models, to decellularize nerves. The new method is based on soaking the nerve tissues in decellularizing solutions while associating ultrasounds and freeze–thaw cycles. It is performed without interrupting the sterility chain, so that the new graft may not require post-production γ-ray irradiation, which is suspected to affect the structural and functional quality of tissues. The new method is rapid, safe, and inexpensive if compared with available commercial ANAs. Histology and immunohistochemistry have been adopted to evaluate the new decellularized nerves. The study shows that the new method can be applied to human nerve samples, obtaining similar, and, sometimes better, results compared with the chosen control method, the Hudson technique.     

四倍体刺槐组培瓶苗生根培养研究

应用正交设计法研究6-BA,NAA及琼脂等3个因子对四倍体刺槐组培苗生根率的影响,试验按正交表L16(45)形成3因素、4水平的不同配比。试验结果表明:最佳的增殖培养基是1/2MS+6-BA0.5mg/L+NAA0.1mg/L+琼脂6g/L。     

化工生产对总控工素质及技术的要求

以聚氯乙烯化工生产过程为例,针对化工总控工的具体工作内容、专业技能和心理素质等方面进行分析。在化工生产中,化工总控工不但要熟知岗位任务和职责,还要有过硬的专业知识、良好的心理素质。生产中,要求化工总控工明确理解化工生产反应原理,并在出现问题时及时有效进行工艺调整。只有具有专业知识技术,能提出合理化的建议,并不断增强个人综合素质,化工总控工才能保障化工生产安全,提高产品质量,为化工行业的可持续发展创造有利条件。     

Healing Pattern Analysis for Dental Implants Using the Mechano-Regulatory Tissue Differentiation Model

(1) Background: Our aim is to reveal the influence of the geometry designs on biophysical stimuli and healing patterns. The design guidelines for dental implants can then be provided. (2) Methods: A two-dimensional axisymmetric finite element model was developed based on mechano-regulatory algorithm. The history of tissue differentiation around eight selected implants can be predicted. The performance of the implants was evaluated by bone area (BA), bone-implant contact (BIC); (3) Results: The predicted healing patterns have very good agreement with the experimental observation. Many features observed in literature, such as soft tissues covering on the bone-implant interface; crestal bone loss; the location of bone resorption bumps, were reproduced by the model and explained by analyzing the solid and fluid biophysical stimuli and (4) Conclusions: The results suggested the suitable depth, the steeper slope of the upper flanks, and flat roots of healing chambers can improve the bone ingrowth and osseointegration. The mechanism related to solid and fluid biophysical stimuli were revealed. In addition, the model developed here is efficient, accurate and ready to extend to any geometry of dental implants. It has potential to be used as a clinical application for instant prediction/evaluation of the performance of dental implants.