Structure and properties of tussah silk fibers graft-copolymerized with methacrylamide and 2-hydroxyethyl methacrylate

Tussah silk fibers were graft-copolymerized with methacrylamide (MAA) and 2-hydroxyethyl methacrylate (HEMA) in aqueous media, using a chemical redox system as an initiator. High weight gain values were obtained with both grafting agents (up to 175%). The extent of homopolymerization was negligible for the MAA grafting system over the entire range of monomer–silk ratios examined, while polymer deposition on the fiber surface occurred when the HEMA–silk ratio exceeded 0.5% (w/w). The moisture content of poly(MAA)-grafted silk fibers was enhanced by grafting. Breaking load, elongation at break, and energy decreased at low weight gain (0–20%) and then remained rather constant. The DSC curves of poly(MAA)-grafted silk showed a new endotherm at about 280°C, due to the melting of poly(MAA) chains. The loss modulus peak of poly(HEMA)-grafted silk fibers broadened and shifted to a lower temperature, showing a tendency to split into two peaks at high weight gain. On the other hand, grafting with poly(MAA) induced a noticeable upward shift of the loss peak. The TMA curves showed that grafting with poly(MAA) resulted in a higher extent of fiber contraction from room temperature to about 250°C. Moreover, the intensity of the final contraction step at about 350°C decreased with increasing weight gain and shifted to a lower temperature. The Raman spectra of grafted fibers were characterized by overlapping of the characteristic lines of both silk fibroin and polymer, the latter showing an intensity proportional to the amount of weight gain. Among the conformationally sensitive vibrational modes of tussah silk fibroin, the amide III range was significantly modified by grafting with both poly(MAA) and poly(HEMA). © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 67:1393–1403, 1998     

Structure and dyeability of Bombyx mori silk fibers with different filament sizes

This study deals with the analysis of structure, physical properties, and dyeing behavior of silk fibers with different filament sizes. Fine and coarse silk fibers were obtained from Akebono and Ariake cocoon varieties, respectively. Both samples exhibited a fairly similar x-ray crystallinity, while the degree of molecular orientation increased with decreasing the fiber size. Tensile strength and energy of fine silk fibers were significantly higher, while elongation at break did not change in relation to the fiber size. Fine silk fibers exhibited a slightly higher thermal stability, as shown by the upward shift of both the DSC decomposition temperature and the TMA final extension step at above 300°C. The TGA and DMA (E″) patterns remained unchanged regardless of fiber size. The amino acid analysis confirmed the absence of any difference of chemical structure between fine and coarse silk fibers, the content of acidic, basic, and other characteristic amino acid residues being exactly the same. Accordingly, both samples adsorbed the same amount of hydrochloric acid. Ex-haustion dyeing tests with various direct, acid, and reactive dyes showed the occurrence of appreciable differences in the perceived color between fine and coarse silk fibers. The size of color difference was quantitatively evaluated by reflectance measurements and discussed in relation to silk fiber morphology, structure, as well as dyeing conditions. The kinetics of diffusion of two model dyes was not significantly affected by the different fiber size and structure. © 1996 John Wiley & Sons, Inc.     

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信息技术的进化,不可思议地降低了信息费用,急剧增加了信息利用者,制造业面临生产主导型的大量生产模式向消费者主导型的订货生产模式的迫切转换,在此时代的转换点,我们提倡“ITonMT”的设想作为制造业强化竞争力的指针,从同时具有应用IT（用IT）和提供IT的生产手段（作IT）两种立场的机床业发展出发,在此介绍实现“ITonMT”的设想的工具IT广场。     

Peptidyl human heart chymase inhibitors. 1. Synthesis and inhibitory activity of difluoromethylene ketone derivatives bearing P'' binding subsites

Appropriate structural modification of the difluoromethylene ketone derivatives at both P3 and P' positions led us to the discovery of peptidyl human heart chymase inhibitor 12h which shows potent activity with Ki = 6 nM and high selectivity against closely related serine protease bovine alpha-chymotrypsin (chymotrypsin Ki = > 100 microM). Using the compound 12b, a docking study with human heart chymase was carried out to presume probable interactions.     

Physical properties of wool fibers modified with isocyanate compounds

Wool fibers were chemically modified with various kinds of isocyanates and diisocyanates. The reactivity of these modifying agents was examined as a function of the reaction solvent, temperature, time, and isocyanate chemistry. The use of dimethyl sulfoxide as the solvent, aliphatic mono and bifunctional isocyanates, such as dodecyl isocyanates and hexamethylene diisocyanate, and a temperature of 75°C resulted in higher weight gains. The moisture content of wool fibers tended to decrease with increasing the weight gain, the extent of which depended on the isocyanate used. Monofunctional isocyanates caused a sharp drop of tensile strength and an increase of elongation at break, while bifunctional isocyanates preserved the intrinsic tensile properties of wool. The FTIR spectra showed changes in the amide I, II, and III ranges, in the CO stretching range at 1750–1700 cm^?1, and in the CH stretching and bending regions at 3000–2800 and 1500–1350 cm^?1, respectively, attributable to the incorporation of the modifying agent. DSC measurements highlighted remarkable changes in the thermal behavior of acylated wool fibers. The bimodal melting endotherm at 230–240°C shifted to lower temperature, and the relative intensity of the constituent peaks changed as a function of the weight gain. Foreign deposits adhering to the surface of chemically modified wool fibers were detected by SEM analysis. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 1390–1396, 2003     

Bilirubin helps to overcome the two-cell block in mouse oocyte cultures

PURPOSE: In vitro fertilization and culture of mouse oocytes, under normal atmospheric oxygen tension, subjects them to severe oxidative stress. Oocytes from some strains of mice lack the natural protective mechanism that guards them against this oxidative stress and fail to develop beyond the two-cell stage. METHODS: We could overcome the toxic effects of oxygen metabolites by adding 0.2-0.4 mg/dl bilirubin in a lactate-pyruvate culture medium defined by Whitten (1971). Six- to 8-week-old ICR (Institute of Cancer Research) female mice were super ovulated by intra peritoneal injection of 5 IU PMSG (pregnant mare serum gonadotropin) followed by 10 IU hCG 48 h later. The oocytes were collected from the distended fallopian tubes and inseminated with 1-2 million sperm from 3-4-month-old ICR male mice. The eggs were scored at 24, 48, and 72 h after the hCG injection. CONCLUSIONS: With 0.4 mg/dl bilirubin supplement, by the end of 72 h, 82% of the eggs progressed from the two-cell stage to the four-cell stage. Routine inclusion of bilirubin can improve embryo development in vitro.     

The deposition mechanism of atmospheric pressure glow plasma polymerized hexafluoropropene: Gas phase analysis of HFP plasma

The relationship between the plasma conditions and the atmospheric pressure glow plasma deposition characteristics of the polyhexafluoropropene film, such as the film configuration, the deposition rate and products in plasma, was investigated. The higher deposition rate and the higher monomer use efficiency were obtained at a lower hexafluoropropene (monomer) concentration and a lower total gas flow rate (longer residence time in the plasma region). However, an extreme long residence time generated some granular deposits. And five gas phase products were detected by gas phase analysis. We considered that C₂F₄ and C₄H₈, which have double bond, were related to the deposition deeply.     

Spherical ultrasonic motor drive system for camera orientation in pipe inspection

We propose a camera actuating system using a spherical ultrasonic motor for inspection of the inside wall of a small pipe. The spherical ultrasonic motor has advantages that include three degrees of freedom, high responsiveness and high accuracy all within a compact body. We describe here the development of an outer rotor spherical ultrasonic motor (OR-SUSM) that enables a camera to rotate by more than 360° along the side of the pipe. All components, including the OR-SUSM, the sensing system, and the electric circuits, are designed to be assembled in the pipe inspection device with outer diameter of 52?mm. To control the system, the phase difference and frequency of the applied voltages are used. The rotational direction is determined by the phase difference and the angular velocity is controlled by the frequency. The completed system can be controlled to within 2° in an experimental pipe inspection test.     

Low temperature formation of luminescent Si nanocrystals with combined process of excimer UV-light irradiation and RTA

Si ion implantation was widely used to synthesize specimens of SiO₂ containing supersaturated Si and subsequent high temperature annealing induces the formation of embedded luminescent Si nanocrystals. In this work, the potentialities of excimer UV-light (172 nm, 7.2 eV) irradiation and rapid thermal annealing (RTA) to achieve low temperature (below 1000 °C) formation of luminescent Si nanocrystals in SiO₂ have been investigated. The Si ions were introduced at acceleration energy of 180 keV to fluences of 7.5 × 10¹⁶ and 1.5 × 10¹⁷ ions/cm². The implanted samples were subsequently irradiated with an excimer-UV lamp for 2 h. After the process, the samples were rapidly thermal annealed at 1050 °C for 5 min before furnace annealing (FA) at 900 °C. Photoluminescence spectra were measured at various stages at the process. Effective visible photoluminescence is found to be observed even after FA at 900 °C, only for specimens treated with excimer-UV lamp and RTA, prior to a low temperature FA process. Based on our experimental results, we discuss the mechanism for the initial formation process of the luminescent Si nanocrystals in SiO₂, together with the effects with excimer lamp irradiation and RTA process on the luminescence.     

Grafting of vinyl monomers onto silk using redox systems. Yellowing of silk

The aim of this study is to investigate the influence of temperature, initiator concentration, and vinyl monomer on silk yellowing during grafting. A series of silk fabrics was treated at four different temperatures (70, 75, 80, and 88°C), with different concentrations of initiator in the range 1–4% owf, with and without methacrylamide (MAA) or 2-hydroxyethyl methacrylate (HEMA). By treating silk with ammonium persulphate (APS), in the absence of a monomer, the degree of silk yellowing increased linearly with increasing both initiator concentration and treatment temperature, indicating that the initiator plays a specific role in enhancing silk yellowing through macroradical formation. The graft copolymerization of MAA (with APS as the initiator) caused only slight changes in the intensity of silk yellowing compared to blank-treated fabrics. On the other hand, the use of HEMA resulted in a deeper yellowing of silk fabrics, especially in the 70–80°C temperature range, due to its higher reactivity and to the tendency to form a homopolymer, leaving unreacted macroradicals on silk fibroin backbone. Compared to APS, other initiators, such as 2,2′-azobis(isobutyronitrile) (AIBN) and 2–2′-azobis-(2-amidino propane) dihydrochloride (ADC), caused a significantly lower degree of silk yellowing when tested in the absebce of a monomer. The yellowness of silk fabrics tended to increase by grafting with HEMA, while decreased by grafting with MAA. The use of variable amounts of monomer (25–150% owf) did not influence the degree of yellowing with ADC as the initiator. The results reported in this study show that the extent of yellowing induced on silk fabrics by grafting MAA and HEMA with APS as the initiator can be limited by a suitable selection of the processing parameters (initiator concentration, temperature). Moreover, the use of both AIBN and ADC appears promising, owing to their negligible effect on silk yellowing. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 69: 239–246, 1998