We systematically investigate the formation of nanostructures in magnetron-sputtered Au films using a CO2 laser. By comparing the optical properties and surface morphologies of Au films on different kinds of substrates before and after laser irradiation with different laser powers and irradiation times, we find that the nanostructures are most rapidly formed in the Au film with 5 nm thickness on a thin glass substrate. With the laser power of 6 W and a beam diameter of ~10 mm at the Au film, only a few tens of seconds of irradiation time is sufficient to induce nanostructures with the area size of ~10 mm in the 5 nm Au film on a thin glass substrate.
We demonstrate the rapid in situ synthesis of polymer-metal nanocomposite films using a CO2 laser at 10.6 μm. The mechanism of our method is that the precursor of the metal nanoparticles, i.e., the metallic ions, is very rapidly reduced in the laser-heated polymer matrix without any reducing agent. Unlike other known laser-induced reduction methods using UV lasers, which produce radicals to promote reduction, the CO2 laser energy is mainly absorbed by the glass substrate, and the laser-heated substrate heats the polymer matrix through heat diffusion to promote reduction. The superiority of the use of CO2 lasers over nanosecond visible~UV lasers is also demonstrated in terms of the damage to the film. The developed method can be a new alternative to quickly synthesize a variety of polymer-metal nanocomposite films.
Illudin S from mushroom, such as Omphalotus japonicus and illudens, is a natural sesquiterpene analog with strong antitumor and antiviral activities. These illudins compounds are highly effective against various drug-resistant cancers that show extreme cytotoxicity an in vitro assay. However, it is difficult to obtain a sufficient amount of highly pure illudin S from a natural product by simple, efficient and low-cost purification techniques. Here, we offer to apply the high-speed countercurrent chromatography for the preparative purification of illudin S from mushroom extract. For a two-solvent system, the optimal condition of hexane/ethyl acetate/methanol/water (1/5/1/5, v/v/v/v) was optimized to obtain pure illudin S from a crude extract. This purified component was evaluated by liquid chromatography (high-purity >99%) and tandem mass spectrometry. The yield amounts of illudin S (1.3 mg/about 10 g Omphalotus japonicus) at one running are determined by liquid chromatographic calibration. It is concluded that by requiring a natural material and costeffectiveness, our method represents a significant improvement over complicated techniques for the purification of illudin S from natural materials.
The purpose of this study was to determine whether a lateral wedge insole reduces the external knee adduction moment during slope walking. Twenty young, healthy subjects participated in this study. Subjects walked up and down a slope using 2 different insoles: a control flat insole and a 7° lateral wedge insole. A three-dimensional motion analysis system and force plate were used to examine the knee adduction moment, the ankle valgus moment, and the moment arm of the ground reaction force to the knee joint center in the frontal plane. The lateral wedge insole significantly decreased the moment arm of the ground reaction force, resulting in a reduction of the knee adduction moment during slope walking, similar to level walking. The reduction ratio of knee adduction moment by the lateral wedge insole during the early stance of up-slope walking was larger than that of level walking. Conversely, the lateral wedge insole increased the ankle valgus moment during slope walking, especially during the early stance phase of up-slope walking. Clinicians should examine the utilization of a lateral wedge insole for knee osteoarthritis patients who perform inclined walking during daily activity, in consideration of the load on the ankle joint.
We study the morphological change of crystalline polymer films by annealing using atomic force microscope, X-ray diffraction, and Fourier transform infrared spectroscopy techniques. As typical samples, we employ high-density and low-density polyethylene films prepared by the cast method. After annealing at 135°C for 4 h, the surface roughness of polyethylene films by the atomic force microscope significantly increases, and the crystallite size by the X-ray diffraction also shows some increase, while the Fourier transform infrared spectroscopy spectrum hardly exhibits any change. This can be well explained as a result of the growth of crystal structure by recrystallization during annealing. More interestingly, we find that the choice of the substrate and also the heating/cooling rates for annealing significantly influences the surface roughness of the films.
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