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Glove Box
A glovebox (or glove box) is a sealed container that is designed to allow one to manipulate objects where a separate atmosphere is desired. Built into the sides of the glovebox are gloves arranged in such a way that the user can place their hands into the gloves and perform tasks inside the box without breaking containment. Part or all of the box is usually transparent to allow the user to see what is being manipulated. Two types of gloveboxes exist. The first allows a person to work with hazardous substances, such as radioactive materials or infectious disease agents, and the second allows manipulation of substances that must be contained within a very high purity inert atmosphere, such as argon or nitrogen. It is also possible to use a glovebox for manipulation of items in a vacuum chamber. Inert atmosphere work The gas in a glovebox is pumped through a series of treatment devices which remove solvents, water and oxygen from the gas. Copper metal (or some other finely divid ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Desiccator
Desiccators are sealable enclosures containing desiccants used for preserving moisture-sensitive items such as cobalt chloride paper for another use. A common use for desiccators is to protect chemicals which are hygroscopic or which react with water from humidity. The contents of desiccators are exposed to atmospheric moisture whenever the desiccators are opened. It also requires some time to achieve a low humidity. Hence they are not appropriate for storing chemicals which react quickly or violently with atmospheric moisture such as the alkali metals; a glovebox or Schlenk-type apparatus may be more suitable for these purposes. Desiccators are sometimes used to remove traces of water from an almost-dry sample. Where a desiccator alone is unsatisfactory, the sample may be dried at elevated temperature using Abderhalden's drying pistol. Constituents The lower compartment of the desiccator contains lumps of silica gel, freshly calcined quicklime, Drierite or (not as effective) ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rocky Flats Plant
The Rocky Flats Plant was a U.S. manufacturing complex that produced nuclear weapons parts in the western United States, near Denver, Colorado. The facility's primary mission was the fabrication of plutonium pits, which were shipped to other facilities to be assembled into nuclear weapons. Operated from 1952 to 1992, the complex was under the control of the U.S. Atomic Energy Commission (AEC), succeeded by the Department of Energy (DOE) in 1977. Plutonium pit production was halted in 1989 after EPA and FBI agents raided the facility and the plant was formally shut down in 1992. Operators of the plant (Rockwell) later pleaded guilty to criminal violations of environmental law. At the time, the fine was one of the largest penalties ever in an environmental law case. Cleanup began in the early 1990s, and the site achieved regulatory closure in 2006. The cleanup effort decommissioned and demolished over 800 structures; removed over 21 tons of weapons-grade material; removed ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
HEPA
HEPA (, high-efficiency particulate air) filter, also known as high-efficiency particulate absorbing filter and high-efficiency particulate arrestance filter, is an efficiency standard of air filters. Filters meeting the HEPA standard must satisfy certain levels of efficiency. Common standards require that a HEPA air filter must remove—from the air that passes through—at least 99.95% (ISO, European Standard) or 99.97% (ASME, U.S. DOE) of particles whose diameter is equal to 0.3 μm, with the filtration efficiency increasing for particle diameters both less than and greater than 0.3 μm. HEPA filters capture pollen, dirt, dust, moisture, bacteria (0.2-2.0 μm), virus (0.02-0.3 μm), and submicron liquid aerosol (0.02-0.5 μm). Some microorganisms, for example, ''Aspergillus niger'', ''Penicillium citrinum'', ''Staphylococcus epidermidis'', and ''Bacillus subtilis'' are captured by HEPA filters with photocatalytic oxidation (PCO). A HEPA filter is a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Anaerobic Organism
An anaerobic organism or anaerobe is any organism that does not require molecular oxygen for growth. It may react negatively or even die if free oxygen is present. In contrast, an aerobic organism (aerobe) is an organism that requires an oxygenated environment. Anaerobes may be unicellular (e.g. protozoans, bacteria) or multicellular. Most fungi are obligate aerobes, requiring oxygen to survive. However, some species, such as the Chytridiomycota that reside in the rumen of cattle, are obligate anaerobes; for these species, anaerobic respiration is used because oxygen will disrupt their metabolism or kill them. Deep waters of the ocean are a common anoxic environment. First observation In his letter of 14 June 1680 to The Royal Society, Antonie van Leeuwenhoek described an experiment he carried out by filling two identical glass tubes about halfway with crushed pepper powder, to which some clean rain water was added. Van Leeuwenhoek sealed one of the glass tubes using a flame an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Radiation
In physics, radiation is the emission or transmission of energy in the form of waves or particles through space or through a material medium. This includes: * ''electromagnetic radiation'', such as radio waves, microwaves, infrared, visible light, ultraviolet, x-rays, and gamma radiation (γ) * ''particle radiation'', such as alpha radiation (α), beta radiation (β), proton radiation and neutron radiation (particles of non-zero rest energy) * '' acoustic radiation'', such as ultrasound, sound, and seismic waves (dependent on a physical transmission medium) * ''gravitational wave, gravitational radiation'', that takes the form of gravitational waves, or ripples in the curvature of spacetime Radiation is often categorized as either ''ionizing radiation, ionizing'' or ''non-ionizing radiation, non-ionizing'' depending on the energy of the radiated particles. Ionizing radiation carries more than 10 electron volt, eV, which is enough to ionize atoms and molecules and break ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Neutron Emission
Neutron emission is a mode of radioactive decay in which one or more neutrons are ejected from a nucleus. It occurs in the most neutron-rich/proton-deficient nuclides, and also from excited states of other nuclides as in photoneutron emission and beta-delayed neutron emission. As only a neutron is lost by this process the number of protons remains unchanged, and an atom does not become an atom of a different element, but a different isotope of the same element. Neutrons are also produced in the spontaneous and induced fission of certain heavy nuclides. Spontaneous neutron emission As a consequence of the Pauli exclusion principle, nuclei with an excess of protons or neutrons have a higher average energy per nucleon. Nuclei with a sufficient excess of neutrons have a greater energy than the combination of a free neutron and a nucleus with one less neutron, and therefore can decay by neutron emission. Nuclei which can decay by this process are described as lying beyond the neutron ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Radiation Shielding
Radiation protection, also known as radiological protection, is defined by the International Atomic Energy Agency (IAEA) as "The protection of people from harmful effects of exposure to ionizing radiation, and the means for achieving this". Exposure can be from a source of radiation external to the human body or due to internal irradiation caused by the ingestion of radioactive contamination. Ionizing radiation is widely used in industry and medicine, and can present a significant health hazard by causing microscopic damage to living tissue. There are two main categories of ionizing radiation health effects. At high exposures, it can cause "tissue" effects, also called "deterministic" effects due to the certainty of them happening, conventionally indicated by the unit gray and resulting in acute radiation syndrome. For low level exposures there can be statistically elevated risks of radiation-induced cancer, called "stochastic effects" due to the uncertainty of them happening, conv ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wood Fiber
Wood fibres (also spelled wood fibers, see spelling differences) are usually cellulosic elements that are extracted from trees and used to make materials including paper. The end paper product (paper, paperboard, tissue, cardboard, etc.) dictates the species, or species blend, that is best suited to provide the desirable sheet characteristics, and also dictates the required fibre processing (chemical treatment, heat treatment, mechanical "brushing" or refining, etc.). In North America, virgin (non-recycled) wood fibre is primarily extracted from hardwood (deciduous) trees and softwood (coniferous) trees. The wood fibre can be extracted as a primary product, or collected during the milling of lumber. Wood fibres can also be recycled from used paper materials. Paper Wood fibres are treated by combining them with other additives which break down the fibres into a spongy mass called pulp. The pulp is then processed, and the network of tiny fibres is pressed flat, becoming paper. C ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Polymethyl Methacrylate
Poly(methyl methacrylate) (PMMA) belongs to a group of materials called engineering plastics. It is a transparent thermoplastic. PMMA is also known as acrylic, acrylic glass, as well as by the trade names and brands Crylux, Plexiglas, Acrylite, Astariglas, Lucite, Perclax, and Perspex, among several others ( see below). This plastic is often used in sheet form as a lightweight or shatter-resistant alternative to glass. It can also be used as a casting resin, in inks and coatings, and for many other purposes. Although not a type of familiar silica-based glass, the substance, like many thermoplastics, is often technically classified as a type of glass, in that it is a non-crystalline vitreous substance—hence its occasional historic designation as ''acrylic glass''. Chemically, it is the synthetic polymer of methyl methacrylate. It was developed in 1928 in several different laboratories by many chemists, such as William Chalmers, Otto Röhm, and Walter Bauer, and first brought t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lead
Lead is a chemical element with the symbol Pb (from the Latin ) and atomic number 82. It is a heavy metal that is denser than most common materials. Lead is soft and malleable, and also has a relatively low melting point. When freshly cut, lead is a shiny gray with a hint of blue. It tarnishes to a dull gray color when exposed to air. Lead has the highest atomic number of any stable element and three of its isotopes are endpoints of major nuclear decay chains of heavier elements. Lead is toxic, even in small amounts, especially to children. Lead is a relatively unreactive post-transition metal. Its weak metallic character is illustrated by its amphoteric nature; lead and lead oxides react with acids and bases, and it tends to form covalent bonds. Compounds of lead are usually found in the +2 oxidation state rather than the +4 state common with lighter members of the carbon group. Exceptions are mostly limited to organolead compounds. Like the lighter members of the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Machining
Machining is a process in which a material (often metal) is cut to a desired final shape and size by a controlled material-removal process. The processes that have this common theme are collectively called subtractive manufacturing, which utilizes machine tools, in contrast to ''additive manufacturing'' (3D printing), which uses controlled addition of material. Machining is a part of the manufacture of many metal products, but it can also be used on other materials such as wood, plastic, ceramic, and composite material. A person who specializes in machining is called a machinist. A room, building, or company where machining is done is called a machine shop. Much of modern-day machining is carried out by computer numerical control (CNC), in which computers are used to control the movement and operation of the mills, lathes, and other cutting machines. This increases efficiency, as the CNC machine runs unmanned therefore reducing labour costs for machine shops. History and ter ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
