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
Kingri (string instrument) inserted into the fingerboard with three pegs. The strings on the bow are made by using three tufts of horse hair or Goongaru. The strings on the instrument were originally made of animal gut, but modern day Indian gypsies typically use low quality steel strings instead, resulting in more vibrato and lending the instrument a sound similar to the violin. Sri Lankan composer Dinesh Subasinghe used the kingri on the album Rawan Nada as well as for performing folk music. In 2007, Subasinghe made some modifications to the instrument and discovered it to be another close version of the Ravanstron