For the textile revival of Fukushima,it is necessary to raise individual technology, and to make high value-added products. And it is important that the maker makes an original brand by sending the information of the product. To that end,it is essential to bring up a talented person carrying the next generation. Now we are planning the revival of the textile of Fukushima to a nucleus with hollow silk.
Silk fibroin from Bombyx mori silkworm has outstanding mechanical properties despite being spun from aqueous solution. Now, we have been developing several kinds of biomaterials, such as regeneration materials for bone, cornea and artificial blood vessel. In this paper, we present the applications of silk fibroins to tissue engineering. In the case of blood vessel regeneration, we have developed the small diameter vascular grafts made by silk fibroins. As results, the new grafts from silk fibroins have good patency, and these grafts were commonly covered with cells and platelets at 4 weeks after implantation.
Recently, braiding has attracted a great deal of attention as a configuration for reinforcing fiber-reinforced composites. However, limitations on the availability of appropriate braiding machinery make it difficult to manufacture the wide variety of braids required for various applications. In this report, a novel braiding system is proposed as a flexible method of textile production. Line-tracing robots with microcomputer boards and wireless communication modules are employed as yarn carriers. In the system proposed here there is no central unit that surveys, monitors, or controls the robots; each robot makes its decisions individually on the basis of the information obtained by communication. Nevertheless, the robot program is simple, and the robots are able to perform both cord and flat braiding without the need to change the program.
Gel-like liquid silk samples were collected from the middle division of the silk glands of fully grown larvae of domestic Bombyx mori silkworm 1 day before spinning or cocooning. The samples were then immersed in distilled water and kept at 4°C in a refrigerator for 2 days, during which time the fibroin and sericin molecules gradually dissolved into the water. The liquid silk solution was then cast on a polystyrene dish and dried at 4°C. The as-cast films were subjected to water annealing or immersion in ethanol, or both, and the crystallization behavior of the fibroin fraction was analyzed by wide-angle X-ray measurement. Normally the fibroin shows two types of crystal morphology—silk I or silk II—depending on the crystallization temperature. In the case of liquid silk containing both fibroin and sericin fractions, the fibroin molecules had a silk II crystal morphology after water annealing treatment at room temperature, whereas usually silk I crystal morphology would have been generated if only the fibroin molecules had been treated. A certain mechanism established between the fibroin and sericin fractions seems to have controlled the crystallization behavior of the fibroin.
Vssilk1, a major component of hornet silk produced by larvae of the yellow hornet (Vespa simillima), can be produced as a recombinant protein in Escherichia coli. Here, we successfully fused a tandem repeat of a cell adhesion peptide, Arg-Gly-Asp-Ser (RGDS), to full-length Vssilk1 protein by genetic recombination. The recombinant Vssilk1 protein with the RGDS sequence (Vssilk1-RGDS) was fabricated into a cast film. We observed that more fibroblasts adhered to, and spread out on, the Vssilk1-RGDS film than on a Vssilk1 film.
To easily achieve desalting of a high-molecular-weight sericin (Virgin Sericin) solution on a large scale, we examined the use of a circulating dialysis system. Native-state sericin of high-molecular weight (cocoon shells of Sericin Hope) was dissolved in a lithium bromide aqueous solution, which was then subjected to circulating dialysis. The results indicated that circulating dialysis could be used to desalt Virgin Sericin solution on a large scale; the characteristics of the high-molecular weight sericin were maintained after the dialysis.
6,6'-Dibromoindigo is a major component of the historic pigment ancient purple, also known as Tyrian purple, royal purple, or shellfish purple. Arguably, it is not only the oldest known pigment but also the most expensive and best known. The indigo parent of 6,6'-Dibromoindigo was the subject of the first chemical industry and is now used broadly as a commercial product. We have already synthesized it by referring to the paper by Imming P. et al. 2001, Synth Commun 31:3721-27' and have examined its reduction and dyeing qualities, but to our knowledge its color fastness has never been measured. Tests of the color fastness of this dye consisted of xenon lamp irradiation, rubbing, washing, and perspiration permeation. The fastness of ancient purple was almost the same as, or slightly better than, that of indigo. We concluded that ancient purple has good color fastness after dyeing.
The cocoon shells of several silkworm races contain flavonoids. We recently found that cocoon shells of Ryokuken races such as Daizo contain specific flavonoids that are almost non-existent in cocoon shells of Sasamayu races such as Pure Mysore. Usually, LC-MS systems are used to analyze flavonoids in cocoon shells. However, these systems require a great deal of time and effort to operate and maintain. Here, we confirmed that absorbance at a wavelength of 365 nm of aqueous methanolic extracts of the cocoons was well correlated with the total flavonoid content of the cocoons. The absorbance ratio (A420 nm: A365 nm) of the extracts was correlated with the percentage of Ryokuken-specific flavonoids in the cocoons. We propose a simple analytical method using a UV-VIS photospectrometer to roughly estimate the amount and composition of cocoon flavonoids. This may help in the genetic study and breeding of Ryokuken and Sasamayu races.
The aim of our 4-year long project was to develop highly durable silk koto strings with marked sonority by using the original Japanese races of silkworms. In a previous paper, we reported that there were significant differences in durability and sonority among the silk strings from different races of silkworms. Here, we report the differences in sonority of strings from various races of silkworms in experimental musical performances on the newly developed “silent” koto. Our overall aim was to minimize the reverberation of the instrument itself.
Dupion silk is rougher than regular silk and contains knots and irregularities where the fibers from two different kinds of cocoon are combined. Because there is a shortage of supply of the double cocoons used in dupion silk production, an efficient method of producing double cocoons is needed. A commercial race named N-tama×C-tama, which has a high percentage of double cocoons, has been reported. However, this race has defective reelability. We therefore bred a new race, J701×C701, with improved reelability. About 40% of the larvae of J701×C701 made double cocoons, and the performance characteristics of silk from this race were almost the same as those of silks from ordinary commercial races. The knots of dupion silk reeled from J701×C701 cocoons were slightly smaller than those of J137×C146. The fukurami (fullness and softness) value of fabric made from J701×C701 dupion silk was smaller than that of fabric made from J137×C146 silk. In contrast, the shari (crispness value was greater. We have given the name Shurimaru to J701×C701.
We examined the characteristics of production and marketing in the Fujiyoshida textile production area of Japan in recent years, as well as the importance of related undertakings, with the aim of supporting the survival of local textile production. We interviewd members of Fujiyoshida's weaving cooperatives, staff at the Fuji industrial technology center in Yamanashi Prefecture, and staff of a representative weaving company. We reached the following conclusions. In recent years production has increased and the percentage production of cloth for curtain and wall has increased. The marketing focus is direct sales by the producers and at tourist stalls. We hope to set up plural groups such as the Kaikiza group, that which has been made from four successors, of weaving as soon as possible. We hope to develop original goods and carry out sales promotion by means of direct sales.
We examined production structure and structure in the Tokamachi textile production area from 1955 to 2012, with the ultimate aim of promoting the survival of local small and medium textile-production enterprises there. We interviewed staff at the Cooperative Union Tokamachi Textile Industrial Association and at three representative weaving companies. We found that the scale of production in the area gradually declined between 1975 and 2012 in terms of quantity and shipment of goods; in other words, the production base weakened. At the same time, goods representative of each particular weaving company were produced, but not goods that were representative of the production area as a whole. There are two issues important to the survival of the weaving area. One is the need to begin making goods as soon as possible that are representative of the whole production area. The other is build a system of cooperation over a very wide area with neighboring weaving production areas so as to secure labor for weaving.
We used a new analytical approach to quantitatively investigate the contribution of structural variables in the sericulture industry to changes in cocoon yield in Japan during the period 1915-1996. Variance decomposition analysis revealed that improvements in rearing technology and an increase in the number of cocoon producers before world War II, along with increases in productivity and in the area under mulberry cultivation after the War, were mainly responsible for increased cocoon production. More complex mechanisms underlay the decreases in cocoon production that varied across regions, particularly after the War.
Aqueous solution of calcium chloride (CaCl2) is a promising solvent for biomaterial like silk fibroin, thereby offering potential application in industrial purposes. We observed that the silk, produced by larvae of hornets (Vespa), dissolved in an aqueous solution of CaCl2 in the concentration range of 3-6 M. The solubility of hornet silk was the maximum when CaCl2 concentration was 4.5 M. The rate of dissolution of the hornet silk in the aqueous solution of CaCl2 was sensitive to temperature. The hornet silk was found to dissolve in 4.5 M CaCl2 solution even at 20°C. Such high solubility of the hornet silk in the aqueous solution of CaCl2 could be attributed to the low content of β-sheet structure. The silk dissolved in the aqueous solution of CaCl2 within 1 h when the temperature was between 40 and 80°C, and less protein degradation occurred under the aforementioned condition.
Artificial corneas have been studied in various ways, but promising materials or methods have not yet been established specifically for the corneal stroma. Anatomically, the corneal stroma consists of precisely aligned collagen layers and keratocytes. This unique structure is thought to be associated with corneal transparency. Here, we investigated the use of fibrous material as an artificial corneal stroma. Aligned nanofiber non-woven mats can easily be fabricated from an aqueous fibroin solution by using an electrospinning technique. We evaluated the possibility of using our aligned electrospun fibroin nanofiber mat as a novel artificial corneal stroma. From in vitro experiments, seeded corneal stromal cells migrated into the space of the fibroin fiber mat as well as adhered to the surface. These migrating and adhering cells kept its phenotype. Similar phenomena also confirmed in vivo implantation test. Three weeks after surgery, host-derived corneal stromal cells were migrated into implanted fibroin fiber mat. Inflammatory or immune responses against the implanted fibroin fiber mat were not seen till 3 weeks after surgery. These findings strongly suggest that our fibroin aligned fiber mat will be useful as an artificial cornea. For clinical use we must first improve the mat's transparency.
We compared the characteristics of fabric made of raw silk from Gokuboso 1 silkworm cocoons, which have superfine filaments, with those of fabric from silk of the standard silkworm Syunrei×Shogetsu (SRG). We investigated the fabrics' mechanical, hydrophilic, and thermal properties. The Gokuboso fabric typically displayed reductions in bending rigidity, coefficient of friction, and geometrical roughness, lower moisture content, and greater water vapor permeability than the SRG fabric. No significant difference was noted between the two with regard to evaporative heat resistance, but the dry heat resistance and k value of the Gokuboso fabric were greater than those of the SRG one. These results suggested that the Gokuboso fabric would be cooler in summer and warmer in winter than the SRG.
Traditionally, tsumugi has been seen as a secondary product made from inferior cocoons that cannot be used for raw silk. Nowadays, however, tsumugi is considered to be an important type of fabric. Tsumugi is characterized by variation in thickness of its yarn, which is hand-spun from silk floss, but the details of this variation are unknown. Here, we discuss the distribution of tsumugi yarn width, which is considered to be closely related to thickness. To maintain the integrity of the thread, it is impossible for the yarn to be thinner than a certain value. In contrast, there is no upper limit on the thickness of the tsumugi yarn. We used a truncated normal distribution (TND) to describe this asymmetric situation. The convoluted TND and a normal distribution were obtained for practical analysis of the data. Likelihood equations for estimating the distribution parameters were derived as well. The equations were applied to actual tsumugi yarn-width data captured with an image scanner. The convoluted TND summarized the width distribution of tsumugi yarn well.