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 electronic means (synthesizer), or in some other way. Sometimes, instruments that do not usually have a keyboard, such as the "glockenspiel", are fitted with one. Though they have no moving parts and are struck by mallets held in the player's hands, they have the same physical arrangement of keys and produce soundwaves in a similar manner. The theremin, an electrophone, is played without physical contact by the player. Musical instrument A musical instrument is an instrument created or adapted to make musical sounds. In principle, any object that produces sound can be considered a musical instrument—it is through purpose that