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Detection Of Explosives Traces
Explosives trace detectors (ETD) are explosive detection equipment able to detect explosives of small magnitude. The detection is accomplished by sampling non-visible "trace" amounts of particulates. Devices similar to ETDs are also used to detect narcotics. The equipment is used mainly in airports and other vulnerable areas considered susceptible to acts of unlawful interference. Characteristics Sensitivity Detection limit is defined as the lowest amount of explosive matter a detector can detect reliably. It is expressed in terms of nano-grams (ng), pico-grams (pg) or femto-grams (fg) with fg being better than pg better than ng. It can also be expressed in terms of parts per billion (ppb), parts per trillion (ppt) or parts per quadrillion (ppq). Sensitivity is important because most explosives have a low vapor pressure . The detector with the highest sensitivity is the best in detecting vapors of explosives reliably. Light weight Portable explosive detectors need to be as lig ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Explosive Detection
Explosive detection is a non-destructive inspection process to determine whether a container contains explosive material. Explosive detection is commonly used at airports, ports and for border control. Detection tools Colorimetrics & automated colorimetrics The use of colorimetric test kits for explosive detection is one of the most established, simplest, and most widely used methods for the detection of explosives. Colorimetric detection of explosives involves applying a chemical reagent to an unknown material or sample and observing a color reaction. Common color reactions are known and indicate to the user if there is an explosive material present and in many cases the group of explosives from which the material is derived. The major groups of explosives are nitroaromatic, nitrate ester, and nitramine explosives, as well as inorganic nitrate-based explosives. Other groups include chlorates and peroxides which are not nitro based explosives. Since explosives usually contain ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Exciton
An exciton is a bound state of an electron and an electron hole which are attracted to each other by the electrostatic Coulomb force. It is an electrically neutral quasiparticle that exists in insulators, semiconductors and some liquids. The exciton is regarded as an elementary excitation of condensed matter that can transport energy without transporting net electric charge. An exciton can form when a material absorbs a photon of higher energy than its bandgap. This excites an electron from the valence band into the conduction band. In turn, this leaves behind a positively charged electron hole (an abstraction for the location from which an electron was moved). The electron in the conduction band is then less attracted to this localized hole due to the repulsive Coulomb forces from large numbers of electrons surrounding the hole and excited electron. These repulsive forces provide a stabilizing energy balance. Consequently, the exciton has slightly less energy th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Explosives
An explosive (or explosive material) is a reactive substance that contains a great amount of potential energy that can produce an explosion if released suddenly, usually accompanied by the production of light, heat, sound, and pressure. An explosive charge is a measured quantity of explosive material, which may either be composed solely of one ingredient or be a mixture containing at least two substances. The potential energy stored in an explosive material may, for example, be * chemical energy, such as nitroglycerin or grain dust * pressurized gas, such as a gas cylinder, aerosol can, or BLEVE * nuclear energy, such as in the fissile isotopes uranium-235 and plutonium-239 Explosive materials may be categorized by the speed at which they expand. Materials that detonate (the front of the chemical reaction moves faster through the material than the speed of sound) are said to be "high explosives" and materials that deflagrate are said to be "low explosives". Explosives may ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Secondary Electrospray Ionization
Secondary electro-spray ionization (SESI) is an ambient ionization technique for the analysis of trace concentrations of vapors, where a nano-electrospray produces charging agents that collide with the analyte molecules directly in gas-phase. In the subsequent reaction, the charge is transferred and vapors get ionized, most molecules get protonated (in positive mode) and deprotonated (in negative mode). SESI works in combination with mass spectrometry or ion-mobility spectrometry. History The fact that trace concentrations of gases in contact with an electrospray plume were efficiently ionized was first observed by Fenn and colleagues when they noted that tiny concentrations of plasticizers produced intense peaks in their mass spectra. However, it was not until 2000 when this problem was reframed as a solution, when Hill and coworkers used an electrospray to ionize molecules in the gas phase, and named the technique Secondary Electrospray Ionization. In 2007, the almost simultaneo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mass Spectrometry
Mass spectrometry (MS) is an analytical technique that is used to measure the mass-to-charge ratio of ions. The results are presented as a '' mass spectrum'', a plot of intensity as a function of the mass-to-charge ratio. Mass spectrometry is used in many different fields and is applied to pure samples as well as complex mixtures. A mass spectrum is a type of plot of the ion signal as a function of the mass-to-charge ratio. These spectra are used to determine the elemental or isotopic signature of a sample, the masses of particles and of molecules, and to elucidate the chemical identity or structure of molecules and other chemical compounds. In a typical MS procedure, a sample, which may be solid, liquid, or gaseous, is ionized, for example by bombarding it with a beam of electrons. This may cause some of the sample's molecules to break up into positively charged fragments or simply become positively charged without fragmenting. These ions (fragments) are then separated acco ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
FLIR Systems
Teledyne FLIR LLC (an acronym for "forward-looking infrared"), a subsidiary of Teledyne Technologies, specializes in the design and production of thermal imaging cameras and sensors. Its main customers are governments and in 2020, approximately 31% of its revenues were from the federal government of the United States and its agencies. Operations FLIR produces devices for the following markets: * Surveillance and reconnaissance * Force protection * Border and maritime patrol * Critical infrastructure protection * Search and rescue * Detection * Targeting * Airborne law enforcement * Drug interdiction Facilities The company has offices, manufacturing, and/or research and development facilities in Nashua, New Hampshire; Goleta, California; North Billerica, Massachusetts; Orlando, Florida; Bozeman, Montana; Stillwater, Oklahoma; Arlington County, Virginia; Chelmsford, Massachusetts; Ventura, California; Elkridge, Maryland; Freeport, Pennsylvania; Oak Ridge, Tennessee; Wat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Defense Advanced Research Projects Agency
The Defense Advanced Research Projects Agency (DARPA) is a research and development agency of the United States Department of Defense responsible for the development of emerging technologies for use by the military. Originally known as the Advanced Research Projects Agency (ARPA), the agency was created on February 7, 1958, by President Dwight D. Eisenhower in response to the Soviet launching of Sputnik 1 in 1957. By collaborating with academia, industry, and government partners, DARPA formulates and executes research and development projects to expand the frontiers of technology and science, often beyond immediate U.S. military requirements.Dwight D. Eisenhower and Science & Technology, (2008). Dwight D. Eisenhower Memorial CommissionSource ''The Economist'' has called DARPA the agency "that shaped the modern world," and pointed out that " Moderna's COVID-19 vaccine sits alongside weather satellites, GPS, drones, stealth technology, voice interfaces, the personal computer ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fido Explosives Detector
The Fido explosives detector is a battery-powered, handheld sensory device that uses amplifying fluorescent polymer (AFP) materials to detect trace levels of high explosives like trinitrotoluene (TNT). It was developed by Nomadics, a subsidiary of ICX Technologies (now owned by FLIR Systems), in the early 2000s as part of the Defense Advanced Research Projects Agency's (DARPA) Dog's Nose program. The Fido explosives detector is considered the first artificial nose capable of detecting landmines in the real world. The device was named after its ability to detect explosive vapors at concentrations of parts per quadrillion (1 in 10^15), which is comparable to the sensitivity of a bomb-sniffing dog’s nose, i.e. the historical “gold standard” for finding concealed explosives. Overview The Fido explosives detector functions as a trace explosives detector through its use of a specially-made fluorescent polymer film that is extremely sensitive to molecules of TNT, which can be ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Trinitrotoluene
Trinitrotoluene (), more commonly known as TNT, more specifically 2,4,6-trinitrotoluene, and by its preferred IUPAC name 2-methyl-1,3,5-trinitrobenzene, is a chemical compound with the formula C6H2(NO2)3CH3. TNT is occasionally used as a reagent in chemical synthesis, but it is best known as an explosive material with convenient handling properties. The explosive yield of TNT is considered to be the standard comparative convention of bombs and asteroid impacts. In chemistry, TNT is used to generate charge transfer salts. History TNT was first prepared in 1863 by German chemist Julius Wilbrand and originally used as a yellow dye. Its potential as an explosive was not recognized for three decades, mainly because it was too difficult to detonate because it was less sensitive than alternatives. Its explosive properties were first discovered in 1891 by another German chemist, Carl Häussermann. TNT can be safely poured when liquid into shell cases, and is so insensitive that ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nitro Compound
In organic chemistry, nitro compounds are organic compounds that contain one or more nitro functional groups (). The nitro group is one of the most common explosophores (functional group that makes a compound explosive) used globally. The nitro group is also strongly electron-withdrawing. Because of this property, bonds alpha (adjacent) to the nitro group can be acidic. For similar reasons, the presence of nitro groups in aromatic compounds retards electrophilic aromatic substitution but facilitates nucleophilic aromatic substitution. Nitro groups are rarely found in nature. They are almost invariably produced by nitration reactions starting with nitric acid. Synthesis Preparation of aromatic nitro compounds Aromatic nitro compounds are typically synthesized by nitration. Nitration is achieved using a mixture of nitric acid and sulfuric acid, which produce the nitronium ion (), which is the electrophile: + The nitration product produced on the l ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Explosive
An explosive (or explosive material) is a reactive substance that contains a great amount of potential energy that can produce an explosion if released suddenly, usually accompanied by the production of light, heat, sound, and pressure. An explosive charge is a measured quantity of explosive material, which may either be composed solely of one ingredient or be a mixture containing at least two substances. The potential energy stored in an explosive material may, for example, be * chemical energy, such as nitroglycerin or grain dust * pressurized gas, such as a gas cylinder, aerosol can, or BLEVE * nuclear energy, such as in the fissile isotopes uranium-235 and plutonium-239 Explosive materials may be categorized by the speed at which they expand. Materials that detonate (the front of the chemical reaction moves faster through the material than the speed of sound) are said to be "high explosives" and materials that deflagrate are said to be "low explosives". Explosives may ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tandem Mass Spectrometry
Tandem mass spectrometry, also known as MS/MS or MS2, is a technique in instrumental analysis where two or more mass analyzers are coupled together using an additional reaction step to increase their abilities to analyse chemical samples. A common use of tandem MS is the analysis of biomolecules, such as proteins and peptides. The molecules of a given sample are ionized and the first spectrometer (designated MS1) separates these ions by their mass-to-charge ratio (often given as m/z or m/Q). Ions of a particular m/z-ratio coming from MS1 are selected and then made to split into smaller fragment ions, e.g. by collision-induced dissociation, ion-molecule reaction, or photodissociation. These fragments are then introduced into the second mass spectrometer (MS2), which in turn separates the fragments by their m/z-ratio and detects them. The fragmentation step makes it possible to identify and separate ions that have very similar m/z-ratios in regular mass spectrometers. Structu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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