A refrigerator (colloquially fridge) consists of a thermally insulated compartment and a heat pump (mechanical, electronic or chemical) that transfers heat from the inside of the fridge to its external environment so that the inside of the fridge is cooled to a temperature below the room temperature. Refrigeration is an essential food storage technique in developed countries. The lower temperature lowers the reproduction rate of bacteria, so the refrigerator reduces the rate of spoilage. A refrigerator maintains a temperature a few degrees above the freezing point of water. Optimum temperature range for perishable food storage is 3 to 5 °C (37 to 41 °F).[1] A similar device that maintains a temperature below the freezing point of water is called a freezer. The refrigerator replaced the icebox, which had been a common household appliance for almost a century and a half.
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The application of the pyrethrum chrysanthemum can be directly processed into a powder, and the extract can be processed into a propellant, an aerosol, a cream oil, a mosquito coil, and the like. Due to the instability of light and heat, it cannot be used to control agricultural pests. Mainly used for the prevention and control of sanitary pests, such as mosquitoes, flies, cockroaches, fleas, lice, bed bugs, etc., can also be used to prevent pests in stored grain, such as rice elephants, wheat moths, ancestors and other people. Adding synergist at the time of use can increase efficacy and reduce dosage. With the development of some efficient, stable, and safe pyrethroid insecticides, their use has also declined.
Plant Pesticides Pyrethrins
An inhibitory nerve plant derived from pyrethrum in contact with a plant-derived pesticide. Trade name pyrethrum, insoluble in water, soluble in many organic solvents. Low toxicity to higher animals, flower components can cause dermatitis, and even special allergies, can eliminate this effect in the preparation of goods. It is toxic to aquatic animals such as fish and bees. The insecticidal activity is higher and it is a nerve agent. It mainly acts as a contact.