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
Musical instrument important, provides only possible classification for each instrument. The most common types of instrument classifications are strings, brass, woodwind, and percussion. An ancient Hindu system named the "Natya Shastra", written by the sage Bharata Muni and dating from between 200 BC and 200 AD, divides instruments into four main classification groups: instruments where the sound is produced by vibrating strings; percussion instruments with skin heads; instruments where the sound is produced by vibrating columns of air; and "solid", or non-skin, percussion instruments. This system was adapted to some degree in 12th-century Europe by Johannes de Muris, who used the terms