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 more artistic approach and develop experimental musical instruments, often meant for individual playing styles developed by the builder himself. Regardless of how the sound in an instrument is produced, many musical instruments have a keyboard as the user-interface. Keyboard instruments are any instruments that are played with a musical keyboard. Every key generates one or more sounds; most keyboard instruments have extra means (pedals for a piano, stops and a pedal keyboard for an organ) to manipulate these sounds. They may produce sound by wind being fanned (organ) or pumped (accordion), vibrating strings either hammered (piano) or plucked (harpsichord), by