Biodegradable polymer which, edible films have gained more attention due to their environmentally-friendly characteristics, vast variety and availability, non-toxicity, and low cost. Biodegradable polymers have a long history, and since many are natural products, the precise timeline of their discovery and use cannot be accurately traced. One of the first medicinal uses of a biodegradable polymer was the catgut suture, which dates back to at least 100 AD. The first catgut sutures were made from the intestines of sheep, but modern catgut sutures are made from purified collagen extracted from the small intestines of cattle, sheep, or goats. The concept of synthetic
Koto (instrument) Koto (instrument) The is a Japanese stringed musical instrument derived from the Chinese zheng, and similar to the Mongolian yatga, the Korean gayageum, and the Vietnamese đàn tranh. The koto is the national instrument of Japan. Koto are about length, and made from "kiri" wood ("Paulownia tomentosa"). They have 13 strings that are usually strung over 13 movable bridges along the width of the instrument. There is also a 17-string variant. Players can adjust the string pitches by moving the white bridges before playing. To play the instrument, the strings are plucked using three finger picks (thumb, index finger, and