ELASTOHYDRODYNAMIC LUBRICATION ANALYSIS OF LAYERED LINE CONTACT BY THE BOUNDARY ELEMENT METHOD

This paper presents a numerical routine to compute the contact characteristics of elastomer layered cylinders lubricated by isoviscous liquids. The indentation of the elastic layer is calculated from boundary integral equations which are solved by linear and quadratic boundary element methods for a finite plane model and a circular representation of the junction. The hydrodynamic equation is also transformed into a boundary integral equation and solved by Simpson's rule. Some factors which possibly affect numerical accuracy are examined. Examples for finite plane and circular layer are analysed with reference to parameters for printing press roller contact, in which results are obtained for the indentation, film thickness and liquid pressure, as well as internal stresses through the simultaneous solution of the elasticity and hydrodynamic equations. The results show that high precision is easily achieved and the method is efficient for such layered problems.     

色度域亮度域信息融合的监控视频重压缩取证

为解决当前视频重压缩取证方法没有考虑色度域信息、取证准确度低的问题,提出一种面向最新多用途视频编码(versatile video coding, VVC)标准色度域亮度域信息融合的监控视频重压缩取证方法(CLF-SVRF)。基于VVC标准的编码原理,从监控视频的色度域和亮度域维度分析并确定VVC视频码流中与压缩次数密切相关的基础码流特征;基础码流特征包括色度域和亮度域编码单元(coding unit, CU)的划分类型及预测模式;结合拉格朗日率失真优化技术分析随着压缩次数的增加,色度域亮度域CU划分类型和预测模式的变化;进一步确定色度域亮度域CU划分类型和预测模式可以作为检测视频压缩次数的基础码流特征;接着考虑视频监控应用对重压缩取证方法低复杂度的需求,基于色度域亮度域CU划分类型和预测模式构建低复杂度高级码流特征;将高级码流特征输入支持向量机完成监控视频的重压缩取证。实验结果表明,与当前先进方法相比,CLF-SVRF方法的监控视频重压缩取证准确度平均提升了13.53%,同时可以大幅度地降低重压缩取证耗时,重压缩取证时间平均减少了47.42%。     

血清样品中胆固醇的携带式测定仪的开发

利用色谱原理开发荧光芯片,并测定了血清中的总胆固醇含量。分析系统由荧光色谱芯片和荧光阅读器组成,荧光色谱芯片包括塑料盒和纸条,显色剂(AEC),胆固醇氧化酶(CO),胆固醇酯酶(CE),过氧化氢酶(HRP)混合溶液喷在纸条上。在1—4mg/mL浓度范围内,胆固醇标准溶液和荧光强度的变化有线性关系(r=0．979),其回收率为106．5％-94％。该法测定的结果和Hitachi 747全自动生化分析仪有良好的相关性(r=0．895)。本研究所开发的总胆固醇测定方法有操作简单,快速(8min),取样量少(5μL)的特点,适合于携带式测定仪的开发。     

Comparison of Sterilizing Effect of Nonequilibrium Atmospheric-Pressure He/O2 and Ar/O2 Plasma Jets

The sterilizing effect of the non-equilibrium atmospheric pressure plasma jet by applying it to the Bacillus subtilis spores is invesigated. A stable glow discharge in argon or helium gas fed with active gas （oxygen）, was generated in the coaxial cylindrical reactor powered by the radio-frequency power supply at atmospheric pressure. The experimental results indicated that the efficiency of killing spores by making use of an Ar/O2 plasma jet was much better than with a He/O2 plasma jet. The decimal reduction value of Ar/O2 and He/O2 plasma jets under the same experimental conditions was 4.5 seconds and 125 seconds, respectively. It was found that there exists an optimum oxygen concentration for a certain input power, at which the sterilization efficiency reaches a maximum value. It is believed that the oxygen radicals are generated most efficiently under this optimum condition.     

Microenvironmental regulation of stem cells injected in the area at risk of neurodegenerative diseases

The complex mechanism of degenerative diseases and the non-specific modulation of regenerative targets are topics that need to be elucidated in order to advance the use of stem cells in improvement of neurodegenerative diseases. From pre-transplantation through post-transplantation, there are many changes in the conditions, both inside and outside of the stem cells that have not been carefully considered. This has hindered development in the field of cell therapy and regeneration. This viewpoint highlights the potential implications of intracellular and extracellular alterations of stem cells in transplanted areas at risk of neurodegenerative disease.     

Mesenchymal stem cells,the secretome and biomaterials: Regenerative medicine application

Mesenchymal stem cells (MSCs) are multipotent cells usually isolated from bone marrow, endometrium, adipose tissues, skin, and dental pulp. MSCs played a crucial role in regenerative therapy and have been introduced as an interdisciplinary field between cell biology and material science. Recently, MSCs have been widely explored for their application in regenerative medicine and COVID-19 treatment. Different approaches to evaluate the future of biomaterials and stem cell properties have been developed. However, misconceptions and ethical issues still exist, such as MSCs being non-angiogenic, anti-apoptotic, and immunoregulatory competencies. Embryonic stem cells isolation primarily requires the consent of donors and can include the killing of fertilized eggs. These issues generate questions related to ethical and moral issues. However, MSCs have gained considerable attention for tissue regeneration owing to their differentiation ability with immunomodulatory effects. They are capable of secreting a broad range of biomolecules such as proteins, nucleic acids, exosomes, microRNAs, and membrane vesicles, collectively known as secretomes. Secretomes are released in response to the surrounding microenvironment. In this article, we briefly address topics related to the therapeutic potential of MSCs as an advanced approach in the field of regenerative medicine and various perspectives.     

Mean-square stability of stochastic differential time-lag systems

Two sets of sufficient conditions for the mean-square asymptotic stability of the equilibrium state of linear differential time-lag systems with non-stationary random coefficients are derived. Each of the sets of sufficient conditions is then shown to be equivalent to a corresponding unconstrained optimization problem. Hence, it can readily be solved by standard efficient optimization techniques. The usual trial-and-error method of finding the required parameters to satisfy the stability conditions can now be avoided.     

Analysing the natural resting aspects of a complex part

This papers introduces a new approach to predicting the natural resting behaviour of a prismatic part of irregular cross-section. The methods proposed by Boothroyd et al. (1972) and Boothroyd and Ho (1977) were successful in analyzing parts with geometrically simple configurations, although empirical factors were used in the former case. For the past 16 years or so, however, no attempt has been made to analyze pans with complex shapes. Up to now, the study of the natural resting behaviour of complex shapes was conducted by approximating or simplifying the two stated methods. Considering the fact that most parts encountered in industry are not geometrically simple, this practice is the norm rather than the exception. The hypothesis presented in this paper proposes that the probability of apart coming to rest on any of its many feasible resting surfaces is directly proportional to the centroid solid angle and inversely proportional to the height of the centroid from that surface. No empirical factors are needed or assumed. Complex components, such as those with a displaced centre of gravity, can be analyzed thus. The proposed hypothesis is compared with Boothroyd's Energy Barrier Method. The predictions of the hypothesis and the empirical results of drop tests conducted on non-symmetrical (oblong) and symmetrical (T-shaped( prisms are consistent to within 7%. This is the first successful attempt in the analysis of the natural behaviour of components with a complex shape.