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
Jinghu (instrument) Jinghu (instrument) The jinghu (京胡; pinyin: jīnghú) is a Chinese bowed string instrument in the "huqin" family, used primarily in Beijing opera. It is the smallest and highest pitched instrument in the "huqin" family. Like most of its relatives, the "jinghu" has 2 strings that are customarily tuned to the interval of a 5th which the hair of the non-detachable bow passes in between. The strings were formerly made of silk, but in modern times are increasingly made of steel or nylon. Unlike other "huqin" instruments ("erhu", "gaohu", "zhonghu", etc.) it is made of bamboo. Its cylindrical soundbox is covered