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Andersen Sampler
An Andersen sampler, Andersen impactor, or sieve impactor is a cascade impactor used to determine the amount of viable pathogens in a given area, in particular bacteria and fungi. Unlike real-time electronic particle counters, the Andersen sampler imparts pathogens on petri dishes, which require incubation. Thus, calculation of the contaminated air requires working backwards from the resulting pathogen growth in each dish. Andersen samplers have been used to assess the nature of pathogenic aerosols in various scientific papers. It can also be used to study inert aerosols, when each stage of the sampler is used to model respiratory particle deposition. Operation Andersen's paper from 1958 describes a six-stage Andersen sampler that counts "viable airborne particles". In each stage, air goes through specifically sized holes, past a petri dish that aerosols impact, before subsequently moving through smaller holes towards the other petri dishes. Each stage gradually increases the v ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Andersen Six Stage Sampler Schematic
Andersen () is a Danish- Norwegian patronymic surname meaning "son of Anders" (itself derived from the Greek name " Ανδρέας/Andreas", cf. English Andrew). It is the fifth most common surname in Denmark, shared by about 3.2% of the population. From the same root – the given name ''Andreas'' – derives the ''Andreasen'' (cognate '''') and '' Andresen'' . The numbers of bearers of the surnames Andersen, Andreasen, Andrea ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Anthrax
Anthrax is an infection caused by the bacterium '' Bacillus anthracis'' or ''Bacillus cereus'' biovar ''anthracis''. Infection typically occurs by contact with the skin, inhalation, or intestinal absorption. Symptom onset occurs between one day and more than two months after the infection is contracted. The skin form presents with a small blister with surrounding swelling that often turns into a painless ulcer with a black center. The inhalation form presents with fever, chest pain, and shortness of breath. The intestinal form presents with diarrhea (which may contain blood), abdominal pains, nausea, and vomiting. According to the U.S. Centers for Disease Control and Prevention, the first clinical descriptions of cutaneous anthrax were given by Maret in 1752 and Fournier in 1769. Before that, anthrax had been described only in historical accounts. The German scientist Robert Koch was the first to identify ''Bacillus anthracis'' as the bacterium that causes anthrax. Anthra ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Particle Counter
A particle counter is used for monitoring and diagnosing particle contamination within specific clean media, including air, water, and chemicals. Particle counters are used to support clean manufacturing practices in a variety of industrial applications. Clean manufacturing is required for the production of many electronic components and assemblies, pharmaceutical drug products and medical devices, and industrial technologies such as oil and gas. Technology Particle counters function primarily using the principles of light scattering, although other technologies may also be employed. Light scattering by particles use instrumentation comprising a high-intensity light source (a laser), a controlled media flow (air, gas or liquid) and highly sensitive light-gathering detectors (a photo detector). Laser optical particle counters employ five major systems: #Lasers and optics: A laser operates on a single wavelength, so the light source is consistent with constant power output to i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bioaerosol
Bioaerosols (short for biological aerosols) are a subcategory of particles released from terrestrial and marine ecosystems into the atmosphere. They consist of both living and non-living components, such as fungi, pollen, bacteria and viruses. Common sources of bioaerosols include soil, water, and sewage. Bioaerosols are typically introduced into the air via wind turbulence over a surface. Once in the atmosphere, they can be transported locally or globally: common wind patterns/strengths are responsible for local dispersal, while tropical storms and dust plumes can move bioaerosols between continents. Over ocean surfaces, bioaerosols are generated via sea spray and bubbles. Bioaerosols can transmit microbial pathogens, endotoxins, and allergens to which humans are sensitive. A well-known case was the meningococcal meningitis outbreak in sub-Saharan Africa, which was linked to dust storms during dry seasons. Other outbreaks linked to dust events including ''Mycoplasma'' pneumoni ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Particulate Matter Sampler
A particulate matter sampler is an instrument for measuring the properties (such as mass concentration or chemical composition) of particulates in the ambient air. Types Two different types of particulate matter samplers exist that measure particulate mass concentration: manual samplers and automated samplers. Manual Manual samplers draw a known volume of air through a filter. The filter is weighed on an analytical balance before and after sampling, and the difference in weight divided by the volume of air pulled through the filter gives the mass concentration of the particulate. Automated Automated samplers do the weighing in the field. There are two types of automated samplers in common usage: samplers that use a beta gauge for mass measurement and samplers that use a tapered element oscillating microbalance (TEOM) for mass measurement. Beta gauge Beta gauge particulate samplers have an appearance that is similar to a reel to reel tape recorder. Air is pulled through ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aerosol Impaction
In the physics of aerosols, aerosol impaction is the process in which particles are removed from an air stream by forcing the gases to make a sharp bend. Particles above a certain size possess so much momentum that they can not follow the air stream and strike a collection surface, which is available for later analysis of mass and composition. Removal of particles from an air-stream by impaction followed by mass and composition analysis has always been a different approach as to filter sampling, yet has been little utilized for routine analysis because of lack of suitable analytical methods. Advantages The most clear and important advantage of impaction, as opposed to filtration, is that two key aerosol parameters, size and composition, can be simultaneously established. There are many advantages of imp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mineral Oil
Mineral oil is any of various colorless, odorless, light mixtures of higher alkanes from a mineral source, particularly a distillate of petroleum, as distinct from usually edible vegetable oils. The name 'mineral oil' by itself is imprecise, having been used for many specific oils, since 1771. Other names, similarly imprecise, include 'white oil', 'paraffin oil', 'Liquid paraffin (medicinal), liquid paraffin' (a highly refined medical grade), (Latin), and 'liquid petroleum'. Most often, mineral oil is a liquid obtained from Oil refinery, refining crude oil to make gasoline and other petroleum products. Mineral oils used for lubrication are known specifically as base oils. More generally, mineral oil is a Transparency and translucency, transparent, colorless oil, composed mainly of alkanes and cycloalkanes, related to petroleum jelly. It has a density of around . Nomenclature Some of the imprecision in the definition of the names used for mineral oil (such as 'white oil') ref ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
US Army
The United States Army (USA) is the primary land service branch of the United States Department of Defense. It is designated as the Army of the United States in the United States Constitution.Article II, section 2, clause 1 of the United States Constitution (1789).See alsTitle 10, Subtitle B, Chapter 301, Section 3001 It operates under the authority, direction, and control of the United States secretary of defense. It is one of the six armed forces and one of the eight uniformed services of the United States. The Army is the most senior branch in order of precedence amongst the armed services. It has its roots in the Continental Army, formed on 14 June 1775 to fight against the British for independence during the American Revolutionary War (1775–1783). After the Revolutionary War, the Congress of the Confederation created the United States Army on 3 June 1784 to replace the disbanded Continental Army.Library of CongressJournals of the Continental Congress, Volume 27/ref> Th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
2001 Anthrax Attacks
The 2001 anthrax attacks, also known as Amerithrax (a portmanteau of "United States, America" and "anthrax", from its FBI case name), occurred in the United States over the course of several weeks beginning on September 18, 2001, one week after the September 11 attacks. Letters containing anthrax spores were mailed to several news media offices and to senators Tom Daschle and Patrick Leahy, killing five people and infecting 17 others. Capitol Police Officers and staffers working for Senator Russ Feingold were exposed as well. According to the Federal Bureau of Investigation, FBI, the ensuing investigation became "one of the largest and most complex in the history of law enforcement". A major focus in the early years of the investigation was bioweapons expert Steven Hatfill, who was eventually exonerated. Bruce Edwards Ivins, a scientist at the government's biodefense labs at Fort Detrick in Frederick, Maryland, became a focus around April 4, 2005. On April 11, 2007, Ivins was put u ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Livestock
Livestock are the Domestication, domesticated animals that are raised in an Agriculture, agricultural setting to provide labour and produce diversified products for consumption such as meat, Egg as food, eggs, milk, fur, leather, and wool. The term is sometimes used to refer solely to animals which are raised for consumption, and sometimes used to refer solely to farmed ruminants, such as cattle, sheep, and goats. The breeding, maintenance, slaughter and general subjugation of livestock called ''animal husbandry'', is a part of modern agriculture and has been practiced in many cultures since humanity's transition to farming from hunter-gatherer lifestyles. Animal husbandry practices have varied widely across cultures and periods. It continues to play a major economic and cultural role in numerous communities. Livestock farming practices have largely shifted to intensive animal farming. Intensive animal farming increases the yield of the various commercial outputs, but also nega ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cascade Impactor
Cascade, or Cascading may refer to: Science and technology Science * Air shower (physics), a cascade (particle shower) of subatomic particles and ionized nuclei **Particle shower, a cascade of secondary particles produced as the result of a high-energy particle interacting with dense matter * Cascade, the CRISPR-associated complex for antiviral defense (a protein complex) * Cascade (grape), a type of fruit *Cascade waterfalls, or series of waterfalls * Biochemical cascade, a series of biochemical reactions, in which a product of the previous step is the substrate of the next * Collision cascade, a set of nearby adjacent energetic collisions of atoms induced by an energetic particle in a solid or liquid * Ecological cascade, a series of secondary extinctions triggered by the primary extinction of a key species in an ecosystem * Energy cascade, a process important in turbulent flow and drag by which kinetic energy is converted into heat * Trophic cascade, an interaction that can occ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bioaerosol
Bioaerosols (short for biological aerosols) are a subcategory of particles released from terrestrial and marine ecosystems into the atmosphere. They consist of both living and non-living components, such as fungi, pollen, bacteria and viruses. Common sources of bioaerosols include soil, water, and sewage. Bioaerosols are typically introduced into the air via wind turbulence over a surface. Once in the atmosphere, they can be transported locally or globally: common wind patterns/strengths are responsible for local dispersal, while tropical storms and dust plumes can move bioaerosols between continents. Over ocean surfaces, bioaerosols are generated via sea spray and bubbles. Bioaerosols can transmit microbial pathogens, endotoxins, and allergens to which humans are sensitive. A well-known case was the meningococcal meningitis outbreak in sub-Saharan Africa, which was linked to dust storms during dry seasons. Other outbreaks linked to dust events including ''Mycoplasma'' pneumoni ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
