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Microstructured Optical Arrays
Microstructured optical arrays (MOAs) are instruments for focusing x-rays. MOAs use total external reflection at grazing incidence from an array of small channels to bring x-rays to a common focus. This method of focusing means that MOAs exhibit low absorption. MOAs are used in applications that require x-ray focal spots in the order of few micrometers or below, such as radiobiology of individual cells. Current MOA-based focusing optics designs have two consecutive array components in order to reduce comatic aberration. Properties MOAs are achromatic (which means the focal properties do not change for radiation of different wavelengths) as they utilize grazing incidence reflection. This means that they are able to focus chromatic radiation to a common point unlike zone plates. MOAs are also adjustable as the optic can be compressed to alter the focal properties such as focal length. Focal length can be calculated for the system in fig. 1 using the geometry shown in fig. 2 where i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
X-ray Optics
X-ray optics is the branch of optics that manipulates X-rays instead of visible light. It deals with focusing and other ways of manipulating the X-ray beams for research techniques such as X-ray crystallography, X-ray fluorescence, small-angle X-ray scattering, X-ray microscopy, X-ray phase-contrast imaging, and X-ray astronomy. Since X-rays and visible light are both electromagnetic waves they propagate in space in the same way, but because of the much higher frequency and photon energy of X-rays they interact with matter very differently. Visible light is easily redirected using lenses and mirrors, but because the real part of the complex refractive index of all materials is very close to 1 for X-rays, they instead tend to initially penetrate and eventually get absorbed in most materials without changing direction much. X-ray techniques There are many different techniques used to redirect X-rays, most of them changing the directions by only minute angles. The most common princ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
MOA Config 2 Geometry
Moa are extinct giant flightless birds native to New Zealand. The term has also come to be used for chicken in many Polynesian cultures and is found in the names of many chicken recipes, such as Kale moa and Moa Samoa. Moa or MOA may also refer to: People * Moa (name) * Mohammed Abdellaoue (born 1985), Norwegian football player nicknamed "Moa" * Moa Lignell (born 1994), Swedish singer * Moa Kikuchi (菊地 最愛 Kikuchi Moa, born July 4, 1999), a Japanese idol, singer, and model. Places ;Islands * Moa (Indonesia), one of the Leti Islands * Moa Island (Queensland), in Australia ;Malls * Mall of Alnor, in Maguindanao, Philippines * Mall of America, in Minnesota, United States * SM Mall of Asia, in Manila, Philippines ;Rivers * Moa River, in west Africa * Moa River (Brazil) * Moa River (Cuba) ;Towns and villages * Moa, Cuba * Moa, Niger Moa, Niger is a village and rural commune in Niger ) , official_languages = , languages_type = National languages [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cell Nucleus
The cell nucleus (pl. nuclei; from Latin or , meaning ''kernel'' or ''seed'') is a membrane-bound organelle found in eukaryotic cells. Eukaryotic cells usually have a single nucleus, but a few cell types, such as mammalian red blood cells, have no nuclei, and a few others including osteoclasts have many. The main structures making up the nucleus are the nuclear envelope, a double membrane that encloses the entire organelle and isolates its contents from the cellular cytoplasm; and the nuclear matrix, a network within the nucleus that adds mechanical support. The cell nucleus contains nearly all of the cell's genome. Nuclear DNA is often organized into multiple chromosomes – long stands of DNA dotted with various proteins, such as histones, that protect and organize the DNA. The genes within these chromosomes are structured in such a way to promote cell function. The nucleus maintains the integrity of genes and controls the activities of the cell by regulating gene expres ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cytoplasm
In cell biology, the cytoplasm is all of the material within a eukaryotic cell, enclosed by the cell membrane, except for the cell nucleus. The material inside the nucleus and contained within the nuclear membrane is termed the nucleoplasm. The main components of the cytoplasm are cytosol (a gel-like substance), the organelles (the cell's internal sub-structures), and various cytoplasmic inclusions. The cytoplasm is about 80% water and is usually colorless. The submicroscopic ground cell substance or cytoplasmic matrix which remains after exclusion of the cell organelles and particles is groundplasm. It is the hyaloplasm of light microscopy, a highly complex, polyphasic system in which all resolvable cytoplasmic elements are suspended, including the larger organelles such as the ribosomes, mitochondria, the plant plastids, lipid droplets, and vacuoles. Most cellular activities take place within the cytoplasm, such as many metabolic pathways including glycolysis, and proces ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cell (biology)
The cell is the basic structural and functional unit of life forms. Every cell consists of a cytoplasm enclosed within a membrane, and contains many biomolecules such as proteins, DNA and RNA, as well as many small molecules of nutrients and metabolites.Cell Movements and the Shaping of the Vertebrate Body in Chapter 21 of Molecular Biology of the Cell '' fourth edition, edited by Bruce Alberts (2002) published by Garland Science. The Alberts text discusses how the "cellular building blocks" move to shape developing embryos. It is also common to describe small molecules such as ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bystander Effect (radiobiology)
The radiation-induced bystander effect (bystander effect) is the phenomenon in which unirradiated cells exhibit irradiated effects as a result of signals received from nearby irradiated cells. In November 1992, Hatsumi Nagasawa and John B. Little first reported this radiobiological phenomenon. Effect There is evidence that targeted cytoplasmic irradiation results in mutation in the nucleus of the hit cells. Cells that are not directly hit by an alpha particle, but are in the vicinity of one that is hit, also contribute to the genotoxic response of the cell population. Similarly, when cells are irradiated, and the medium is transferred to unirradiated cells, these unirradiated cells show bystander responses when assayed for clonogenic survival and oncogenic transformation. This is also attributed to the bystander effect. Demonstration The demonstration of a bystander effect in 3D human tissues and, more recently, in whole organisms have clear implication of the potential relev ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Microprobe
A microprobe is an instrument that applies a stable and well-focused beam of charged particles (electrons or ions) to a sample. Types When the primary beam consists of accelerated electrons, the probe is termed an electron microprobe, when the primary beam consists of accelerated ions, the term ion microprobe is used. The term microprobe may also be applied to optical analytical techniques, when the instrument is set up to analyse micro samples or micro areas of larger specimens. Such techniques include micro Raman spectroscopy, micro infrared spectroscopy and micro LIBS. All of these techniques involve modified optical microscopes to locate the area to be analysed, direct the probe beam and collect the analytical signal. A laser microprobe is a mass spectrometer that uses ionization by a pulsed laser and subsequent mass analysis of the generated ions. Uses Scientists use this beam of charged particles to determine the elemental composition of solid materials (minerals, glasses, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Plasma (physics)
Plasma () 1, where \nu_ is the electron gyrofrequency and \nu_ is the electron collision rate. It is often the case that the electrons are magnetized while the ions are not. Magnetized plasmas are ''anisotropic'', meaning that their properties in the direction parallel to the magnetic field are different from those perpendicular to it. While electric fields in plasmas are usually small due to the plasma high conductivity, the electric field associated with a plasma moving with velocity \mathbf in the magnetic field \mathbf is given by the usual Lorentz force, Lorentz formula \mathbf = -\mathbf\times\mathbf, and is not affected by Debye shielding. Mathematical descriptions To completely describe the state of a plasma, all of the particle locations and velocities that describe the electromagnetic field in the plasma region would need to be written down. However, it is generally not practical or necessary to keep track of all the particles in a plasma. Therefore, plasma physicist ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Haber–Bosch Process
The Haber process, also called the Haber–Bosch process, is an artificial nitrogen fixation process and is the main industrial procedure for the production of ammonia today. It is named after its inventors, the German chemists Fritz Haber and Carl Bosch, who developed it in the first decade of the 20th century. The process converts atmospheric nitrogen (N2) to ammonia (NH3) by a reaction with hydrogen (H2) using a metal catalyst under high temperatures and pressures: : \ce \quad \Delta H^\circ = -91.8~\text Though this reaction is exothermic (i.e. it releases energy, albeit not very much), it results in a decrease in entropy, which is the central reason why it is very challenging to carry out. Before the development of the Haber process, it had been difficult to produce ammonia on an industrial scale, with early methods, such as the Birkeland–Eyde process and the Frank–Caro process, all highly inefficient. During World War I, the Haber process provided Germany with a sou ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Deep Reactive Ion Etching
Deep reactive-ion etching (DRIE) is a highly anisotropic etch process used to create deep penetration, steep-sided holes and trenches in wafers/substrates, typically with high aspect ratios. It was developed for microelectromechanical systems (MEMS), which require these features, but is also used to excavate trenches for high-density capacitors for DRAM and more recently for creating through silicon vias ( TSVs) in advanced 3D wafer level packaging technology. In DRIE, the substrate is placed inside a reactor, and several gases are introduced. A plasma is struck in the gas mixture which breaks the gas molecules into ions. The ions accelerated towards, and react with the surface of the material being etched, forming another gaseous element. This is known as the chemical part of the reactive ion etching. There is also a physical part, if ions have enough energy, they can knock atoms out of the material to be etched without chemical reaction. DRIE is a special subclass of RIE. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Silicon
Silicon is a chemical element with the symbol Si and atomic number 14. It is a hard, brittle crystalline solid with a blue-grey metallic luster, and is a tetravalent metalloid and semiconductor. It is a member of group 14 in the periodic table: carbon is above it; and germanium, tin, lead, and flerovium are below it. It is relatively unreactive. Because of its high chemical affinity for oxygen, it was not until 1823 that Jöns Jakob Berzelius was first able to prepare it and characterize it in pure form. Its oxides form a family of anions known as silicates. Its melting and boiling points of 1414 °C and 3265 °C, respectively, are the second highest among all the metalloids and nonmetals, being surpassed only by boron. Silicon is the eighth most common element in the universe by mass, but very rarely occurs as the pure element in the Earth's crust. It is widely distributed in space in cosmic dusts, planetoids, and planets as various forms of silicon dioxide ( ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
MOA Config 2
Moa are extinct giant flightless birds native to New Zealand. The term has also come to be used for chicken in many Polynesian cultures and is found in the names of many chicken recipes, such as Kale moa and Moa Samoa. Moa or MOA may also refer to: People * Moa (name) * Mohammed Abdellaoue (born 1985), Norwegian football player nicknamed "Moa" * Moa Lignell (born 1994), Swedish singer * Moa Kikuchi (菊地 最愛 Kikuchi Moa, born July 4, 1999), a Japanese idol, singer, and model. Places ;Islands * Moa (Indonesia), one of the Leti Islands * Moa Island (Queensland), in Australia ;Malls * Mall of Alnor, in Maguindanao, Philippines * Mall of America, in Minnesota, United States * SM Mall of Asia, in Manila, Philippines ;Rivers * Moa River, in west Africa * Moa River (Brazil) * Moa River (Cuba) ;Towns and villages * Moa, Cuba * Moa, Niger * Moa, Mkinga District, in Tanga Region, Tanzania Ship of the New Zealand Navy * ''Moa'' class patrol boat, built between 1978 and 1985 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
