[en] Short communication

[en] Solid-state polycondensation process of recycled polyethylene-terephthalate and its effect on crystalline structure and mechanical properties were investigated. A three-phase morphological model was applied for the evaluation of crystalline structure, while mechanical properties were determined by dynamic mechanical analysis. The effect of solid-state polycondensation process on morphology was investigated and described in detail. A new method was used to analyze the effect of solid-state polycondensation process on mechanical properties. Relationship was found between evolved crystalline structure and storage modulus of samples.

No abstract available

[en] Large aperture, low mass, thin vacuum windows are required to minimize beam loss in the beam lines of particle accelerators as the products of nuclear collisions move from upstream targets to downstream detectors. This article describes the design, fabrication, testing, and operating experience of a large rectangular vacuum window, 122 cmx61 cm, and two circular windows of 91.4 and 96.5 cm diam. These window designs utilize a composite Kevlar 29 fabric and Mylar laminate as a window material with a typical combined thickness of 0.35 mm. Data for several material thicknesses are also presented. The windows are usually designed to withstand a pressure differential of two to three atmospheres to achieve the required factor of safety. These windows are typically used in the medium vacuum range of 10^-4 Torr. The equations used to predict the behavior of the window material will also be discussed

[en] Microfibers (MFs) have recently become an increasingly prevalent pollutant in ecosystems and pose a direct threat to organisms and an indirect threat via adsorption of other pollutants. Here, we used Caenorhabditis elegans to study multigenerational effects of polyethylene terephthalate (PET) MFs (diameter 17.4 μm) by observing the maternal generation (P0) to the seventh offspring generation (F7) with continuous MF exposure. Exposure to 250-μm PET MFs decreased locomotion behavior and induced intestinal reactive oxygen species (ROS) in the P0 generation compared with other PET MF sizes. Moreover, no notably negative effects on survival were observed in any generation during continuous exposure to 250-μm PET MFs. However, the reproduction rate clearly decreased in the F2 and F3 generations but gradually recovered in the F4–F7 generations. Developmental abnormalities showed a close relationship with body length. Although some recovery was confirmed, there were significant decreases in body length in the F2–F5 generations. Interestingly, growth inhibition was also observed in the F6 generation without MF exposure. ROS production and dermal damage in the P0–F5 generations might have resulted in the toxicological responses. To the best of our knowledge, this is the first study to provide evidence of multigenerational toxicity of MFs in C. elegans.

No abstract available

[en] Periodic nanostructures were formed on a polyethylene terephthalate (PET) film surface with a femtosecond laser. The PET is clinically applied for biomaterials such as an artificial blood vessel, an artificial ligament, and soft tissue material because of having weather resistance, chemical resistance and bio inert property. When the PET was implanted in human body, proteins and cells were adhered randomly to grow from living body tissues. If the cell adherence is controlled by the material itself, it is possible to enhance the proliferation of living body tissue. In our previous study, the periodic nanostructures were formed on a TiO2 film by femtosecond laser irradiation. In cell cultivated test on the treated TiO2 film, cells elongations along the grooves of the periodic nanostructures were observed. From the results, it was indicated that the periodic structure could control the direction of cell elongations. It was important for control of cells elongation to form tissue orientation and 3D cell cultivation. However, only limited research has been reported to form the periodic structure on plastic surface with an excimer laser or ion beam. In this study, a new method of periodic nanostructure formation on PET surface was developed with femtosecond laser at wavelength of 1045 nm. In order to evaluate the surface morphology, atomic force microscopy (AFM) analysis was conducted on treated and un-treated PET surface. A cell (MG-63) cultivated test were carried out on the treated and un-treated PET surface. (author)

[en] Dynamic frictional sliding behaviour between two homogenous Homalite blocks is studied. The blocks are initially held together using a constant compressive stress. The sliding motion is initiated by impacting one of the blocks with an external object. The resulting sliding modes are inspected. Initiation of fretting is examined by studying the opening stresses in the interface. (paper)

[en] We study the adsorption of anionic surfactant, sodium dodecyl diphenyloxide disulfonate (SDDD) on three types of polyethylene terephthalate (PET) substrates from aqueous solutions of SDDD of different concentrations. Neutral electrolyte (KCl) was added to the solutions to vary the ionic strength. Three types of substrates were used: 1) original PET film; 2) etched nonporous film, obtained from pristine film by chemical etching and bearing negative charge on the surface; 3) etched porous membranes, fabricated from pristine film by ion irradiation and subsequent chemical etching. The membranes have negative charge on the flat surface and on the inner pore walls. The comparison shows that the negative charge on the flat surface has weak effect on adsorption of the anionic surfactant, and the SDDD adsorption on the inner walls of pores is much weaker than on flat surface, even if the pore radius is significantly larger than the Debye length. This «exclusion» effect strongly depends on ionic strength of solution.

[en] Electric field plays a key role in producing required nanofibers in electrospinning. The applied voltage and working distance are the two main factors affects the electric field distribution during the electrospinning process. This work discussed the effects of these two parameters on the fiber fineness and performance in the electrospinning process, and also verified the results of numerical simulation through a series of experiments. The results showed that the larger the voltage applied to the spinneret is, the greater the electric force acting on the fibers is, which leads to a smaller fiber fineness and a preferable hydrophobic performance and strength. On the other hand, as the spinning distance increases, the smaller the force exerted on the fiber is, the larger the diameter is and the weaker hydrophobic performance is. (paper)