Electronic cigarette

An electronic cigarette, also known as an e-cigarette, Personal Vaporizer or PV, is an electronic inhaler that vaporizes a liquid solution into an aerosol mist, simulating the act of tobacco smoking. Electronic cigarettes are no longer marketed as smoking cessation aids or tobacco replacement in most countries, including the United States; however, widespread anecdotal evidence[vague] from PV users credits the devices with having provided long-term success with smoking cessation. There may be similarities between conventional and some electronic cigarettes in the physical design and the nicotine release, which may approximate the same amount of nicotine as a conventional cigarette. There are also many electronic cigarettes which do not resemble conventional cigarettes at all. The amount of nicotine contained can also be chosen by the user with some people choosing no nicotine at all. The benefits and risks of electronic cigarette use are a subject of uncertainty among health organizations and researchers. Limited controlled studies are available due to the relatively recent invention of the device. Laws vary widely concerning the use and sale of electronic cigarettes and accompanying liquid solutions, with pending legislation and ongoing debate in many regions. The primitive concept of an electronic cigarette can be traced to an idea by Herbert A. Gilbert, who in 1963 patented a device described as "a smokeless non-tobacco cigarette" that involved "replacing burning tobacco and paper with heated, moist, flavored air." This device heated the nicotine solution and produced steam. In 1967, Gilbert was approached by several companies interested in manufacturing it, but it was never commercialized and disappeared from the public record after 1967. Hon Lik, a Chinese pharmacist, is widely credited with the invention of the first generation electronic cigarette. In 2000, he came up with the idea of using a piezoelectric ultrasound-emitting element to vaporize a pressurized jet of liquid containing nicotine diluted in a propylene glycol solution. This design produces a smoke-like vapor that can be inhaled and provides a vehicle for nicotine delivery into the bloodstream via the lungs. He also proposed using propylene glycol to dilute nicotine and placing it in

a disposable plastic cartridge which serves as a liquid reservoir and mouthpiece. These inventions are the basis of the present-day electronic cigarettes. The device was first introduced to the Chinese domestic market in May 2004 as an aid for smoking cessation and replacement. The company that Hon Lik worked for, Golden Dragon Holdings, changed its name to Ruyan (, literally "Resembling smoking"), and started exporting its products in 2005–2006 before receiving its first international patent in 2007. The second generation electronic cigarette, or modern electronic cigarette, was invented and introduced to market in 2008 by Dr. Yunqiang Xiu before receiving its international patents in 2009 & UK patent in 2011. The modern electronic cigarette featured the “tankomizer” (or sealed tank system and sealed atomizer technology). This is more useful for Pharmaceutical and medical devices industries. Ultrasound is a cyclic sound pressure wave with a frequency greater than the upper limit of the human hearing range. Ultrasound is thus not separated from "normal" (audible) sound based on differences in physical properties, only the fact that humans cannot hear it. Although this limit varies from person to person, it is approximately 20 kilohertz (20,000 hertz) in healthy, young adults. Ultrasound devices operate with frequencies from 20 kHz up to several gigahertz. Ultrasound is used in many different fields. Ultrasonic devices are used to detect objects and measure distances. Ultrasonic imaging (sonography) is used in human and veterinary medicine. In non-destructive testing of products and structures, ultrasound is used to detect invisible flaws. Industrially, ultrasound is used for cleaning and for mixing, and to accelerate chemical processes. Organisms such as bats and porpoises use ultrasound for locating prey and obstacles. Approximate frequency ranges corresponding to ultrasound, with rough guide of some applications A fetus in its mother's womb, viewed at 12 weeks of pregnancy (bidimensional-scan) An ultrasonic examination in East Germany, 1990 Ultrasonics is the application of ultrasound. Ultrasound can be used for imaging, detection, measurement, and cleaning. At higher power levels ultrasonics are useful for changing the chemical properties of substances.