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
Rubab (instrument) a membrane, covering the hollow bowl of the sound-chamber, upon which the bridge is positioned. It has three melody strings tuned in fourths, two or three drone strings and up to 15 sympathetic strings. The instrument is made from the trunk of a mulberry tree, the head from an animal skin such as goat, and the strings either gut (from the intestines of young goats, brought to the size of thread) or nylon. The "rubab" is known as "the lion of instruments" and is one of the two national instruments of Afghanistan (with the zerbaghali). Classical Afghan music often features