Effects of ultraviolet irradiation on the static and dynamic properties of neoprene rubbers

Rubbers deteriorate when they are exposed to ultraviolet irradiation for long periods of time. By conducting a series of hardness measurements and simple tension tests, the static properties of neoprene rubbers before and after exposure to various durations of ultraviolet irradiation were first measured. It is found that the Shore A hardness and tensile modulus of neoprene rubbers after exposure to ultraviolet irradiation are increased but their elongation at break, tensile strength, and energy to break are significantly decreased. On the basis of a complex spring model of a vibration system, the dynamic shear properties of neoprene rubbers before and after exposure to different durations of ultraviolet irradiation were then determined from the experimental results of dynamic transmissibility tests. It is also found that the storage modulus, loss modulus, and loss factor of neoprene rubbers are drastically affected by the duration of ultraviolet irradiation they experienced. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

ZM21镁合金挤压-轧制板材的各向异性研究

研究了ZM21镁合金热挤压板坯及其经过不同累积变形量的横轧和纵轧后板材组织和力学性能的各向异性,力学性能检测包含与板坯挤压方向分别呈0°、45°、90°的方向。结果表明:与挤压态相比较,横轧和纵轧后轧制态合金的强度更高而塑性更低;随着轧制变形量的增加,强度增大,塑性下降。经过挤压-轧制后,原挤压板坯宽度方向抗拉强度最好,原挤压方向最差;伸长率以45°方向为最好,原挤压方向伸长率最差,仅横轧变形量为31.0%时例外,原挤压方向伸长率高达22%。轧后板材伸长率的各向差异受轧制方向的影响比强度更显著,总体上横轧有利于各向异性的控制,其中当横轧变形量为44.8%时,伸长率和抗拉强度的各向异性达到最优组合,各向异性指数IPA分别为7.58%和3.16%。     

Reversal of the Inflammatory Responses in Fabry Patient iPSC-Derived Cardiovascular Endothelial Cells by CRISPR/Cas9-Corrected Mutation

The late-onset type of Fabry disease (FD) with GLA IVS4 + 919G > A mutation has been shown to lead to cardiovascular dysfunctions. In order to eliminate variations in other aspects of the genetic background, we established the isogenic control of induced pluripotent stem cells (iPSCs) for the identification of the pathogenetic factors for FD phenotypes through CRISPR/Cas9 genomic editing. We adopted droplet digital PCR (ddPCR) to efficiently capture mutational events, thus enabling isolation of the corrected FD from FD-iPSCs. Both of these exhibited the characteristics of pluripotency and phenotypic plasticity, and they can be differentiated into endothelial cells (ECs). We demonstrated the phenotypic abnormalities in FD iPSC-derived ECs (FD-ECs), including intracellular Gb3 accumulation, autophagic flux impairment, and reactive oxygen species (ROS) production, and these abnormalities were rescued in isogenic control iPSC-derived ECs (corrected FD-ECs). Microarray profiling revealed that corrected FD-derived endothelial cells reversed the enrichment of genes in the pro-inflammatory pathway and validated the downregulation of NF-κB and the MAPK signaling pathway. Our findings highlighted the critical role of ECs in FD-associated vascular dysfunctions by establishing a reliable isogenic control and providing information on potential cellular targets to reduce the morbidity and mortality of FD patients with vascular complications.     

Plastic deformation of ZnO thin films through edge and screw dislocation movements

Columnar wurtzite grains were formed in sputtered ZnO thin films deposited on a plastic polyethylene terephthalate substrate. Selected-area diffraction patterns reveal that the columnar grains in the sputtered films present two preferred growth planes, namely, the basal (0002) and prismatic (100) growth planes. The diffraction patterns obtained also confirm that the microstructure of sputtered indium tin oxide thin films is amorphous in nature. Tensile tests indicate that the fracture strain of the ZnO thin film occurs between 1.73% and 2.14%, while the fracture strain of the indium tin oxide thin film occurs between 0.24% and 0.67%. Thus, the fracture toughness of the sputtered ZnO thin film is greater than that of the sputtered indium tin oxide thin film. High-resolution transmission electron microscopic images demonstrate that edge and screw dislocations could be identified in the sputtered ZnO thin films. Moreover, edge and screw dislocation movements may, respectively, be observed in the basal- and prismatic-oriented ZnO columnar grains of the sputtered ZnO thin films. Our results indicate that movements of the edge and screw dislocations in the basal- and prismatic-oriented ZnO columnar grains account for the plastic deformation of the investigated ZnO thin films under tensile stress.     

The intelligent on-line monitoring of end milling

The main topics discussed in this paper include sensor integration, data extraction, data processing, monitoring the cutting tool, safety of the tool machinery, and quality of the components in processing. The detection method used in this paper is to extract the workload of a spindle motor from a CNC controller, and then transmit the data via a I/O card for further processing. The computer is connected to the CNC by DNC and is able to detect abnormal conditions and transmit, through DNC, to CNC the NC program to stop the machine or to replace the cutting tool. The systematic architectural instrument develops tools with object-oriented professional software and establishes software structure using a visual component library. The software component structure is made easy for maintaining and extending programs and for the operating system with its graphics user interface.     

Preparation of High-Quality FeV55N Using Ammonia as a Reductant and Nitrogen Source

High-quality FeV55N has been prepared by using ammonia as a reductant and nitrogen source. The raw materials comprised ammonium vanadate and Fe₂O₃, which were first reduced and nitrided by ammonia to prepare FeV55N composite powders of VN and Fe₂N. Subsequently, the composite powders were sintered at high temperature to obtain a bulk FeV55N alloy. The final products obtained by this method do not contain elemental Al, Si, or C impurities. Furthermore, the residual oxygen content of the final products can be reduced to 0.56 wt.%. After sintering, it is possible to obtain a FeV55N alloy with a density of up to 5.4 g/cm³.     

超快速加热退火下保温时间对5083铝合金组织及力学性能的影响

利用Gleeble-3500热模拟系统和电子背散射衍射(EBSD)技术对5083铝合金超快速退火组织的演变规律进行了研究,探讨了5083铝合金经过80％冷轧变形后以500℃/s加热至450℃时,不同保温时间(1～60 s,冷却速度40℃/s)对退火组织及力学性能的影响.结果表明,随退火保温时间从1 s延长到60 s,5...     

Preparation and UV property nickel nanoparticles （〈10 nm） of size-controlled monodisperse by reductive method

Nickel nanoparticles (<10 nm) were successfully synthesized using a reductive method of nickel chloride with sodium borohydride in the ethanol/poly- vinylpyrrolidone (PVP) system. The effects of three factors, such as the concentration of the nickel ions, the time of reaction, and the amount of PVP (surfactant), were discussed. The possible growth process of the particles and optimum reactive conditions was also investigated. The result of transmission electron microscopy (TEM) reveals that these nickel nanoparticles are spherical. The average diameter could be controlled as 2-5 nm under selected conditions. High-resolution TEM and energy-dispersive spectroscopy results indicates that the nickel nanoparticles are pure. The UV-visible light absorption spectrum shows that the peaks of nickel nanoparticles moves toward the short wavelength along with the decrease of sizes.     

Effect of atmosphere control on magnetic properties of CaO-Al2O3-SiO2-Fe3O4 glass ceramics

The influences of atmosphere during processes of melting and heat treatment, heat treatment temperature, Fe₃O₄ content and basicity on the magnetic properties of magnetite-based glass ceramics were investigated. For sample containing 20 % Fe₃O₄ melted in different atmospheres, the highest saturation magnetisation was realized in 20vol% air + 80 vol% Ar, due to the fact that ratio of Fe³⁺ to Fe²⁺ in melt obtained in this atmosphere was close to 2. However, it was found that the coercivity of glass ceramics was not affected by the melting atmosphere. A high sintering temperature led to the decrease of saturation magnetisation and the increase of coercivity. As increasing Fe₃O₄ content, the main crystal phase transformed from CaSiO₃ to CaFe_0.6Al_1.3Si_1.08O₆ and finally to magnetite phase, accompanied by the increase of saturation magnetisation and coercivity. In addition, the increase of basicity caused the decrease of saturation magnetisation and the increase of coercivity.