Time and space dependence of large-scale synthesis of colloidal particle with special morphology and tuneable polymer film architecture

This paper describes a facile method to control the morphology of polymer colloids and the architecture of polymer film via miniemulsion polymerization. By taking advantage of cyclization between the symmetrical diacrylate cross-linker hexamethylene diacrylate (HDDA) and the pendent vinyl in colloidal particles, the morphology of polymer colloids and the architecture of the after-formed polymer film were able to be well controlled by tuning the loading of cross-linker HDDA and crosslinking time. Four kinds of polymer colloid morphologies and four kinds of film architecture (honeycomb, close-packed, loose-packed, and enhanced-honeycomb) were characterized by TEM. The film formation mechanisms behind them were proposed based on the special and interesting results including Z-average size of the colloidal particles, Mc (molecular weight between crosslinking points) and mechanical properties of polymer film. Our results highly suggested that the morphology of polymer colloids and the polymer film architecture together determine the adhesive properties of the colloidal polymer film. The best of 180°-peel resistance, T-peel resistance and shear resistance of the polymer films were 138.12 N/25 mm, 40.98 N/25 mm and 25.72 N/cm² at 2.0 phm, 2.0 phm and 0.4 phm with the same crosslinking time of 90 min, respectively. The proposed method is promising to be scaled up for industrial production due to its well adaptability.     

Practical Application of the Probabilistic‐Statistical Model of the Suspension Separation in Hydrocyclones

An effective practical approach that allows not only a significant reduction in the scope of practical experiments in the course of studying suspension separation processes in hydrocyclones, but also makes it possible to assess the intensity of random components of the processes and define the interrelation between such components and hydrodynamics of flows in a hydrocyclone is presented. Within the frames of the developed probabilistic‐statistical model of suspension separation in hydrocyclones on the basis of statistical self‐similarity properties, a relationship was found between determined and random components of the processes. This allowed transitioning from three‐parameter probability density functions for suspension particles in hydrocyclones to two‐parameter functions; thus significantly improving the efficiency of practical application of the developed model.     

单晶硅表层机械力学特性的各向异性分析

为探究挠性筋结构单晶硅材料的各向异性特性以及KOH腐蚀工艺对其力学性能的影响规律,进行纳米压痕实验,并结合原子力显微镜观察单晶硅表层3个主晶面上压痕裂纹形貌随晶向的变化规律,分析单晶硅材料表层弹性模量、硬度、断裂韧性等机械力学特性参数在(001)、(110)及(111)3个主要晶面上沿各个晶向的变化规律;分析挠性筋结构单晶硅材料(001)晶面的KOH腐蚀工艺对其材料表面机械特性的影响规律.结果表明:挠性筋单晶硅在(001)晶面上弹性模量的各向异性变化幅度明显,硬度及断裂韧性各向异性的变化幅度不大;挠性筋单晶硅在(110)晶面弹性模量和断裂韧性的各向异性变化幅度明显,硬度各向异性变化幅度不大;挠性筋单晶硅在(111)晶面硬度值、弹性模量及断裂韧性参数的变化幅度幅值均较小;确定了单晶硅表层3个晶面裂纹最易扩展的晶向方向,KOH腐蚀工艺使得单晶硅表面质量降低,腐蚀后暴露的表面微裂纹、缺陷等会使得单晶硅(001)晶面表层硬度、断裂韧性降低,从而降低了挠性筋结构的实际断裂强度.     

Ablation behavior of (TiZrHfNbTa)C high-entropy ceramics with the addition of SiC secondary under an oxyacetylene flame

The ablation behavior of high-entropy ceramics (HECs) was investigated in this study using an oxyacetylene flame at 2000 °C. Spark plasma sintering was used to construct a dense HEC (TiZrHfNbTa)C with a 20 vol% of SiC addition (HEC-20SiC). The densification of HEC-20SiC can be improved to a certain extent by adding SiC particles, increasing the hardness of HEC-20SiC to up to 24.6 GPa, and the crack deflection observed through the addition of SiC particles were considered to be the strengthening and toughening mechanisms. After ablation, Hf₆Ta₂O₁₇, Ti_5.1Ta_4.9O₂₀, Nb₂Zr₆O₁₇, TaZr_2.75O₈, and SiO₂ can be detected on an ablated surface and HEC-20SiC possesses the minimum mass ablation rate (?1.9 mg s^?1) and line ablation rate (2.1 μm s^?1) among the comparative ceramics. On the one hand, the SiC phase forms gaseous CO, CO₂, and SiO as well as viscous SiO₂ during ablation and some part of the heat can be dissipated by the evaporation of gaseous CO, CO₂, and SiO; further, pore defects can be healed by viscous SiO₂, thus inhibiting the diffusion of reactive oxygen species. On the other hand, the HEC phase with a lattice-distortion caused by single-phase solid-solution can effectively inhibit the invasion of reactive oxygen species and the outward migration of metal atoms. The invasion rate of reactive oxygen is considered to be the main step during HEC-20SiC ablation, and it is believed that higher principal component HECs can improve ablation performance even further.     

A Metal-Free,Disulfide Oxidized Form of Superoxide Dismutase 1 as a Primary Misfolded Species with Prion-Like Properties in the Extracellular Environments Surrounding Motor Neuron-Like Cells

Superoxide dismutase 1 (SOD1) is a metalloenzyme with high structural stability, but a lack of Cu and Zn ions decreases its stability and enhances the likelihood of misfolding, which is a pathological hallmark of amyotrophic lateral sclerosis (ALS). A growing body of evidence has demonstrated that misfolded SOD1 has prion-like properties such as transmissibility between cells and intracellular propagation of misfolding of natively folded SOD1. Recently, we found that SOD1 is misfolded in the cerebrospinal fluid of sporadic ALS patients, providing a route by which misfolded SOD1 spreads via the extracellular environment of the central nervous system. Unlike intracellular misfolded SOD1, it is unknown which extracellular misfolded species is most relevant to prion-like properties. Here, we determined a conformational feature of extracellular misfolded SOD1 that is linked to prion-like properties. Using culture media from motor neuron-like cells, NSC-34, extracellular misfolded wild-type, and four ALS-causing SOD1 mutants were characterized as a metal-free, disulfide oxidized form of SOD1 (apo-SOD1^S-S). Extracellular misfolded apo-SOD1^S-S exhibited cell-to-cell transmission from the culture medium to recipient cells as well as intracellular propagation of SOD1 misfolding in recipient cells. Furthermore, culture medium containing misfolded apo-SOD1^S-S exerted cytotoxicity to motor neuron-like cells, which was blocked by removal of misfolded apo-SOD1^S-S from the medium. We conclude that misfolded apo-SOD1^S-S is a primary extracellular species that is linked to prion-like properties.     

高熔体流动速率薄壁注塑聚丙烯专用料的结构与性能分析

采用多种分析测试方法，对3类高熔体流动速率薄壁注塑聚丙烯（PP）专用料的熔融结晶性能、光学性能、分子量分布、力学性能、毛细管流变性能、热收缩性能进行了分析研究。结果表明，K1860与2种市售主流PP1、PP2各项性能相当，其中K1860分子量分布相对PP1、PP2较窄，弯曲性能、拉伸性能更优，可满足大型薄壁注塑制品的生产要求。     

Effect of long-chain branching molar fraction on scratch behavior of polypropylene

Polymers containing a certain amount of long-chain-branching (LCB) structure are expected to possess improved mechanical properties over those of the linear structure counterpart. However, fundamental knowledge on the structure–property relationship in LCB containing polypropylene (PP) is still illusive. In the present study, a set of model PP systems containing an increasing molar fraction of LCB (5–19 mol%) were prepared by reactive extrusion to determine how LCB content may influence the scratch behavior of PP. It is shown that with only 5 mol% of LCB content in PP can improve resistance against scratch-induced fish-scale formation by over 25%. The improvement of scratch resistance is attributed to the increases in entanglement density in LCB-containing PPs, which is evidenced by their creep-recovery behavior. The present study demonstrates that the incorporation of LCB in PP leads to higher viscoelastic recovery and increased tensile strength, which account for the observed improvement in scratch performance. The usefulness of LCB in polymers for improving scratch performance is discussed.     

Rubber's dissipated energy quantification used in vibratory insulation and protection systems

In vibratory protection and insulation systems, the major problem consist to choose suitable passive elements (spring, damper, others), which are inserted between the resonator and the exciter which have the role of preventing or reducing the transmission of dynamic forces. This work consists of characterizing a synthetic rubber (SR) sample of hollow circular shape (design requirement) by determining the coefficient of energy dissipation at an average ambient temperature of 20°C with a humidity of 25%. The mechanical load and discharge tests make it possible to draw hysteresis curves through which the dissipation coefficient will be determined, the load values is between 500 and 1000 N, with 30, 60, and 90 mm/min loading speeds and a number of cycles 2, 3, and 5, these values have been chosen so as not to cause the effect of cyclic hardening and softening and also to take into consideration, that the vibration limits movement at 3 cycles, which makes this test different from other tests such as fatigue. The processing of different curves, allows to determine energy dissipation coefficient of rubber specimen and also to examine its variation as a function of load, loading speed, and number of cycles; it is possible to determine other characteristics from this coefficient, such as, damping ratio, dynamic amplification factor, and so on, necessary to study efficiency of protection systems, design, and manufacture, based on the curve of transmissibility of dynamic forces to evaluate performance rubber conditions use.     

Effect of malondialdehyde oxidation on structure and physicochemical properties of amandin

Oil, accounting for 45% of almonds, is easily oxidised and can further induce the protein oxidation to reduce their quality. Structure and physicochemical properties of amandin, the main water-soluble protein in almonds, inducing oxidation by malondialdehyde (MDA) were investigated. The results showed that the content of carbonyl group increased from 5.23 to 33.25 nmol mg⁻¹ of protein with the increase in MDA concentration (P < 0.05). However, the sulphydryl content, surface hydrophobicity, particle size and the absolute value of ζ-potential first increased and then decreased. Fourier-transformed infrared spectroscopy (FT-IR) confirmed that the structure of amandin changed from order to disorder. Fluorescence spectroscopic analysis revealed that mild oxidation (0–0.1 mmol L⁻¹ MDA) exposed hydrophobic groups of the protein. Sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) suggested that protein oxidation promoted crosslinking between protein molecules. Furthermore, protein oxidation markedly declined the total amino acid content of amandin (P < 0.05). In conclusion, MDA oxidation changed the structure and amino acid content of amandin, and caused the protein aggregate and crosslink through hydrophobic interaction and electrostatic interaction.     

Review on development of metal/ceramic interpenetrating phase composites and critical analysis of their properties

Metal/ceramic composites are in high demand in several industries because of their superior thermo-mechanical properties. Among various composite types, the interpenetrating phase composites (IPCs) with percolating metallic and ceramic phases offer manifold benefits, such as a good combination of strength, toughness, and stiffness, very good thermal properties, excellent wear resistance, as well as the flexibility of microstructure and processing route selection, etc. The fabrication of metal/ceramic IPCs typically involves two steps - i) processing of an open porous ceramic body, and ii) infiltration of metallic melt in the pores to fabricate the IPC. Although significant progress has been made in recent years for developing both porous ceramics and melt infiltration methods, to the best of the knowledge of the authors, no review article summarizing all the aspects of processing and properties of IPCs has been published till date. This review article is aimed at filling this gap. Starting with a brief introduction about the current status and applications of IPCs, the various processing routes for fabricating open porous ceramic preforms and melt infiltration techniques have been discussed. Subsequently, the data available for various important physical, mechanical, and thermal properties for IPCs have been critically analyzed to thoroughly understand their dependence on various structural and processing parameters. To compare the properties of IPCs with other relevant materials, seven different Ashby material property maps have been used, and the domains for IPCs have been created in them. For each map, the concept of material indices has been employed to critically discuss how IPCs perform in relation to other material classes for various optimum design conditions. Finally, a detailed future outlook for further research on IPCs has been provided.