Summary This paper reports chemoenzymatic synthesis of amylose-grafted polyacetylenes according to the following reaction manners.
Polymerization of a N-propargylamide monomer having a maltooligosacchairde chain was firstly carried out using a water-soluble Rh-catalyst in water,
giving maltooligosaccharide-grafted polyacetylene. The 1H NMR spectrum of the product supported the structure of the desired polyacetylene. Then, the enzymatic chain-elongation from
the oligosaccharides of the polymer was performed using glucose-1-phosphate catalyzed by phosphorylase to give the polyacetylene
having amylose side-chains. Furthermore, copolymerization of the monomer with the other N-propargylamide monomer was performed under the conditions similar to those of homopolymerization. The phosphorylase-catalyzed
enzymatic chain-elongation of the copolymer was also carried out. The DLS measurement of the amylose-grafted polyacetylenes
in alkaline solution was conducted. 相似文献
A divergent synthesis of cyclitol derivatives has been developed utilizing an N‐heterocyclic carbene‐catalyzed benzoin‐type cyclization of C2‐symmetrical dialdoses. The resulting inososes are versatile intermediates, which are readily converted into not only inositols but also amino‐, deoxy‐, O‐methyl‐ and C‐methyl‐inositols.
This study was undertaken in order to investigate the effect of reduced ambient pressure from an atmospheric pressure (101 kPa) to 0.1 kPa on one-pass full penetration welding of thick high-tensile strength steel plate of 23 mm thickness. A 16 kW disk laser of 1030 nm in wavelength was employed to weld HT980 grade plates at the speed of 5–25 mm/s. In partial penetration welding, it was revealed that humping phenomena occurred easily. Full penetration welding of the high-tensile strength steel plates could not be achieved at 101 kPa. On the other hand, full penetration welding was obtained at the welding speed of less than 20 mm/s at the pressure of less than 10 kPa. Especially, at 0.1 kPa, and 17 and 20 mm/s, sound weld joints without defects were obtained. According to the observation results of a keyhole inlet and a surface molten pool during welding with a high-speed video camera, the melt in front of a keyhole was smaller and the behaviour of a keyhole and a plume was much more stable at 0.1 kPa than at 101 kPa. Moreover, in the full penetration welding, spattering was suppressed under the proper conditions. Such phenomena became more stable in fast welding. It was revealed in laser welding of thick high-tensile strength steel plates that the formation of narrow I-shaped weld beads by achieving full-penetration welding in low vacuum was essential for the production of sound welds without defect. 相似文献
This research develops a new technique for the measurement of interfacial fracture toughness of films/surface coatings using laser-induced ultrasonic waves. Using pulsed laser ablation on the bottom substrate surface, strong stress waves are generated leading to interfacial fractures and coating delamination. Simultaneously, a laser ultrasonic interferometer is used to measure the normal (out-of-plane) displacement of the top surface coating in order to detect coating delamination in a non-destructive manner. We can thus determine the critical laser energy for delamination, yielding the critical stress (that is, the interfacial strength). Subsequently, to examine the interfacial fracture toughness, additional pulsed laser irradiation is applied to a pre-delaminated specimen to show that the delamination area expands. This type of interfacial crack growth can be visualized using laser ultrasonic scanning. Furthermore, the calculation of elastic wave propagation was carried out using a finite-difference time-domain method) in order to accurately estimate the interfacial stress field. In this calculation, the stress distribution around the initial delamination is calculated to obtain the stress intensity factor. Based on the experimental and computational results, interfacial fracture toughness can be quantitatively evaluated. Since this technique relies on a two-laser system in a non-contact approach, it may be useful for a quantitative evaluation of adhesion/bonding quality (including both interfacial fracture strength and toughness) in various environments. 相似文献
Skin cleansers exhibiting less irritation are required. Although most skin cleansers are applied to the skin in a foam state, the amount of surfactant penetrating into the skin is measured in the solution state. Due to the fact that surfactant penetration causes skin irritation, liquid chromatography/mass spectrometry was used in this study to investigate, from the viewpoint of surfactant penetration, the correlation between foam characteristics and the condition of skin treated with foam. Results demonstrated that as the concentration of surfactant in water drainage from the foam decreased, the composition of surfactants in water drainage shifted to contain smaller amounts of longer-chain surfactants, whereas the bubble size of the foam became smaller, notwithstanding any change in compounds. When several bubble sizes of foam were added to the skin, it was confirmed that the amount of surfactant penetrating into the skin depends on the levels in the water drainage. The amount of surfactant penetrating into the skin increased with foam bubble size. It was thought that the surfactant at the gas–liquid interface cannot act freely, and thus surfactants in the water drainage tended to penetrate the skin. These results suggest that along with the type of surfactant, both foam morphology and the actual way in which the foam is produced are also important factors that need to be considered when designing milder cleansers. 相似文献
Concepts of microfactories consisting of microdevices made by micromachine technologies are discussed. A microfactory is
a small production system whose size is very small with respect to the dimensions of the small products. Typical examples
of microfactories are classified according to production types. Microfactory systems have a great possibility to innovate
the production systems of small products by making the best use of the inherent properties of the systems such as miniaturized
facilities, mobility and flexibility. The microfactory saves energy, manufacturing space and mineral resources with decreasing
size of the factory facilities.
Received: 5 August 1996 / Accepted:19 August 1996 相似文献