The behavior of capillary suspensions at diverse length scales: From single capillary bridges to bulk

Liquid-liquid-solid systems are becoming increasingly common in everyday life with many possible applications. Here, we focus on a special case of such liquid-liquid-solid systems, namely, capillary suspensions. These capillary suspensions originate from particles that form a network based on capillary forces and are typically composed of solids in a bulk liquid with an added secondary liquid. The structure of particle networks based on capillary bridges possesses unique properties compared with networks formed via other attractive interactions where these differences are inherently related to the properties of the capillary bridges, such as bridge breaking and coalescence between adjacent bridges. Thus, to tailor the mechanical properties of capillary suspensions to specific requirements, it is important to understand the influences on different length scales ranging from the dynamics of the bridges with varying external stimuli to the often heterogeneous network structure.     

Joint tail of ECOMOR and LCR reinsurance treaties

Researchers in actuarial sciences have investigated the tail behavior of the LCR and ECOMOR reinsurance treaties separately for managing extreme risks in reinsurance business. In practice, a reinsurance company may possess these two treaties simultaneously. Therefore, investigating the joint tail behavior of these two treaties is practically useful in risk management. This paper derives the asymptotic limit of the joint tail of these two reinsurance treaties under the setup of Jiang and Tang (2008).     

Edge agreement of second-order multi-agent system with dynamic quantization via the directed edge Laplacian

This work explores the edge agreement problem of second-order multi-agent systems with dynamic quantization under directed communication. To begin with, by virtue of the directed edge Laplacian, we propose a model reduction representation of the closed-loop multi-agent system depending on the spanning tree subgraph. Considering the limitations of the finite bandwidth channels, the quantization effects of second-order multi-agent systems under directed graph are considered. The static quantizers generally contain a fixed quantization interval and infinite quantization level, which are, to some extent, inefficient and impractical. To further reduce the bit depth (number of bits available) and to obtain better precision, the dynamic quantized communication strategy referring to zooming in-zooming out scheme is required. Based on the reduced model associated with the essential edge Laplacian, the asymptotic stability of second-order multi-agent systems under dynamic quantized effects with only finite quantization level can be guaranteed. Finally, the simulation of altitude alignment of micro air vehicles is provided to verify the theoretical results.     

有界平均振幅空间上的乘法算子

有界平均振幅空间的研究在算子理论及全纯空间的研究中具有重要的作用.主要研究了有界平均振幅空间上乘法算子的性质,并且得到了托普里兹算子有界性及紧性的条件.     

Modeling of cellular pearl chain formation using a double photoconductive layer biochip

A typical double photoconductive layer biochip focusing biological cells and forming specific pearl chains has been studied theoretically in this paper. It was composed of two photoconductive layers coated on the bottom and top of ITO-based glass. A light pattern was used to create face-to-face virtual electrodes and the resulting oscillatory spatial electric field was employed to induce the motion of polarizable neutral particles. In order to estimate the behaviors of the suspended particles, a numerical model including dielectrophoretic forces, dipole–dipole forces and other forces, was implemented by means of the Monte Carlo method. The results indicated that steady-state chains could be formed in a uniform electric field owing to the dipole moment effect. In a non-uniform electric field created by the use of a light pattern, the positive DEP force created a more focused pattern of chains. The work concerning the numerical simulation indicated that this chip could form fixed-length particle chains in perpendicular alignment to satisfy the structured assembly of tissues in the histological engineering application.     

Essential Role of the N- and C-terminals of Laccase from Pleurotus florida on the Laccase Activity and Stability

POXA1b is the most thermostable laccase isoenzyme from Pleurotus ostreatus. POXA1b is remarkably stable at alkaline pH (the t_1/2 at pH 10 was 30 days), and its C-terminal affects its catalytic and stability properties. We cloned POXA1c from P. florida, which showed 99 % identity with POXA1b. POXA1c was functionally expressed in Pichia pastoris. The functions of the N and C termini of POXA1c were investigated using site-directed mutagenesis. Compared with POXA1c, the N-terminal R5V site effectively increased the specific activities for 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) and guaiacol by 2- and 3.5-fold, respectively. A C-terminal truncated mutant, POXA1c△13, also increased the specific activities for ABTS and guaiacol by 2.3- and 3.4-fold, respectively. A double mutant, POXA1cΔ13-R5V, combined the R5V and △13 effects. The specific activity of this double mutant for ABTS was 1,321 U/mg, which indicated a 4-fold increase compared with the wild type. The role of residue V5 on laccase catalytic properties was also observed for laccases from Trametes versicolor and Rigidoporus lignosus. The specific activities of the V5R of the laccases from T. versicolor and R. lignosus were half of that of the wild type. The pH and thermal stability analysis of POXA1c and its mutants showed that the enzymes were remarkably stable because they showed 63 % residual activity after incubation for 108 h at 30 °C over a pH range of 4.5 to 9.0. Similar results were observed for POXA1cΔ13-R5V. POXA1cΔ13-R5V can be widely used in industrial biotechnology because of its excellent catalytic properties.     

管件无模拉伸成形力能参数数学模型研究

对不锈钢管件无模拉伸变形速度场及力能参数进行了理论及实验研究.分析了不锈钢管件无模拉伸的变形模型、速度场以及力能参数的影响因素及影响规律,采用上限法确定了不锈钢管件无模拉伸速度场及力能参数物理模型,填补了国内外关于不锈钢管件无模拉伸变形及力能参数物理模型研究的空白.为不锈钢管件无模拉伸工艺工业化应用奠定基础.     

激光硬化9SiCr表面土壤磨损研究

在壤土、沙土和黏土3种土壤中对激光处理的9SiCr材料进行磨损试验,考察了激光硬化工艺参数对9SiCr 旋耕刀基体显微硬度的影响,获得9SiCr 旋耕刀基体激光硬化处理的最佳工艺参数。结果表明：在激光功率为1 200W、扫描速度为14mm/s和激光功率1500W、扫描速度16mm/s的条件下,磨损率较小。激光处理表面在3种土壤条件下进行了耐磨性比较,沙土对试件的磨损率影响最小。9SiCr经过激光处理其表面耐磨性比一般淬火表面的耐磨性提高约5倍。9SiCr表面磨损形式主要是磨粒磨损。激光处理9SiCr表面提高了表面硬化层的硬度,从而提高了材料的耐磨性,增加了9SiCr的使用寿命。