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Fluorescence Techniques
Fluorescence is one of two kinds of photoluminescence, the emission of light by a substance that has absorbed light or other electromagnetic radiation. When exposed to ultraviolet radiation, many substances will glow (fluoresce) with colored visible light. The color of the light emitted depends on the chemical composition of the substance. Fluorescent materials generally cease to glow nearly immediately when the radiation source stops. This distinguishes them from the other type of light emission, phosphorescence. Phosphorescent materials continue to emit light for some time after the radiation stops. This difference in duration is a result of quantum spin effects. Fluorescence occurs when a photon from incoming radiation is absorbed by a molecule, exciting it to a higher energy level, followed by the emission of light as the molecule returns to a lower energy state. The emitted light may have a longer wavelength and, therefore, a lower photon energy than the absorbed radi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mineralogy
Mineralogy is a subject of geology specializing in the scientific study of the chemistry, crystal structure, and physical (including optical mineralogy, optical) properties of minerals and mineralized artifact (archaeology), artifacts. Specific studies within mineralogy include the processes of mineral origin and formation, classification of minerals, their geographical distribution, as well as their utilization. History Early writing on mineralogy, especially on gemstones, comes from ancient Babylonia, the ancient Greco-Roman world, ancient and medieval History of China, China, and Sanskrit texts from History of India, ancient India and the ancient Islamic world. Books on the subject included the ''Naturalis Historia, Natural History'' of Pliny the Elder, which not only described many different minerals but also explained many of their properties, and Kitab al Jawahir (Book of Precious Stones) by Persian scientist Al-Biruni. The German Renaissance specialist Georgius Agricola ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fluorophore
A fluorophore (or fluorochrome, similarly to a chromophore) is a fluorescent chemical compound that can re-emit light upon light excitation. Fluorophores typically contain several combined aromatic groups, or planar or cyclic molecules with several π bonds. Fluorophores are sometimes used alone, as a tracer in fluids, as a dye for staining of certain structures, as a substrate of enzymes, or as a probe or indicator (when its fluorescence is affected by environmental aspects such as polarity or ions). More generally they are covalently bonded to macromolecules, serving as a markers (or dyes, or tags, or reporters) for affine or bioactive reagents (antibodies, peptides, nucleic acids). Fluorophores are notably used to stain tissues, cells, or materials in a variety of analytical methods, such as fluorescent imaging and spectroscopy. Fluorescein, via its amine-reactive isothiocyanate derivative fluorescein isothiocyanate (FITC), has been one of the most popular fluorophores ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Biofluorescence
Biofluorescence is fluorescence exhibited by a living organism: part of the organism absorbs light or other radiation at one wavelength and emits visible light at another, usually longer. The absorbed radiation is often blue or ultraviolet, while the light emitted is typically green, red, or anything in between. Biofluorescence requires an external light source and a fluorescent biomolecular substance, which is often one or more proteins, but can consist of other biomolecules. A perceptible example of fluorescence occurs when the absorbed radiation is ultraviolet, thus invisible to the human eye, while the emitted light is in the visible spectrum; this gives the fluorescent substance a distinct color that can only be seen when it is exposed to UV light. Since biofluorescence was discovered in ''Aequorea victoria'' and the green fluorescent protein structure was resolved, many other organisms have been shown to exhibit biofluorescence and many new fluorescent proteins have been di ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Incandescent Lamp
An incandescent light bulb, also known as an incandescent lamp or incandescent light globe, is an electric light that produces illumination by Joule heating a filament until it glows. The filament is enclosed in a glass bulb that is either evacuated or filled with inert gas to protect the filament from oxidation. Electric current is supplied to the filament by terminals or wires embedded in the glass. A bulb socket provides mechanical support and electrical connections. Incandescent bulbs are manufactured in a wide range of sizes, light output, and voltage ratings, from 1.5 volts to about 300 volts. They require no external regulating equipment, have low manufacturing costs, and work equally well on either alternating current or direct current. As a result, the incandescent bulb became widely used in household and commercial lighting, for portable lighting such as table lamps, car headlamps, and flashlights, and for decorative and advertising lighting. Incandescent b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
White
White is the lightest color and is achromatic (having no chroma). It is the color of objects such as snow, chalk, and milk, and is the opposite of black. White objects fully (or almost fully) reflect and scatter all the visible wavelengths of light. White on television and computer screens is created by a mixture of red, blue, and green light. The color white can be given with white pigments, especially titanium dioxide. In ancient Egypt and ancient Rome, priestesses wore white as a symbol of purity, and Romans wore white togas as symbols of citizenship. In the Middle Ages and Renaissance a white unicorn symbolized chastity, and a white lamb sacrifice and purity. It was the royal color of the kings of France as well as the flag of monarchist France from 1815 to 1830, and of the monarchist movement that opposed the Bolsheviks during the Russian Civil War (1917–1922). Greek temples and Roman temples were faced with white marble, and beginning in the 18t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
LED Lamps
An LED lamp or LED light is an electric light that produces light using light-emitting diodes (LEDs). LED lamps are significantly more Electrical efficiency, energy-efficient than equivalent Incandescent light bulb, incandescent lamps and fluorescent lamps. The most efficient commercially available LED lamps have efficiencies exceeding 200 lumen (unit), lumens per watt (lm/W) and convert more than half the input power into light. Commercial LED lamps have a lifespan several times longer than both incandescent and fluorescent lamps. LED lamps require an electronic LED circuit to operate from mains power lines, and losses from this circuit means that the efficiency of the lamp is lower than the efficiency of the LED chips it uses. The driver circuit may require special features to be compatible with lamp dimmers intended for use on incandescent lamps. Generally the current waveform contains some amount of distortion, depending on the luminaires' technology. The LED lamp marke ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fluorescent Lamp
A fluorescent lamp, or fluorescent tube, is a low-pressure mercury-vapor gas-discharge lamp that uses fluorescence to produce visible light. An electric current in the gas excites mercury vapor, to produce ultraviolet and make a phosphor coating in the lamp glow. Fluorescent lamps convert electrical energy into visible light much more efficiently than Incandescent light bulb, incandescent lamps, but are less efficient than most LED lamps. The typical luminous efficacy of fluorescent lamps is 50–100 lumens per watt, several times the efficacy of incandescent bulbs with comparable light output (e.g. the luminous efficacy of an incandescent lamp may only be 16 lm/W). Fluorescent lamp fixtures are more costly than incandescent lamps because, among other things, they require a electrical ballast, ballast to regulate Electric current, current through the lamp, but the initial cost is offset by a much lower running cost. Compact fluorescent lamps (CFL) made in the same sizes a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gas-discharge Lamp
Gas-discharge lamps are a family of artificial light sources that generate light by sending an electric discharge through an ionization, ionized gas, a plasma (physics), plasma. Typically, such lamps use a noble gas (argon, neon, krypton, and xenon) or a mixture of these gases. Some include additional substances, such as mercury (element), mercury, sodium, and metal halides, which are vaporized during start-up to become part of the gas mixture. Single-ended self-starting lamps are insulated with a mica disc and contained in a borosilicate glass gas discharge tube (arc tube) and a metal cap. They include the sodium-vapor lamp that is the gas-discharge lamp in street lighting. In operation, some of the electrons are forced to leave the atoms of the gas near the anode by the electric field applied between the two electrodes, leaving these atoms positively ionized. The free electrons thus released flow to the anode, while the cations thus formed are accelerated by the electric fiel ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cathode-ray Tube
A cathode-ray tube (CRT) is a vacuum tube containing one or more electron guns, which emit electron beams that are manipulated to display images on a phosphorescent screen. The images may represent electrical waveforms on an oscilloscope, a Film frame, frame of video on an Analog television, analog television set (TV), Digital imaging, digital raster graphics on a computer monitor, or other phenomena like radar targets. A CRT in a TV is commonly called a picture tube. CRTs have also been Williams tube, used as memory devices, in which case the screen is not intended to be visible to an observer. The term ''cathode ray'' was used to describe electron beams when they were first discovered, before it was understood that what was emitted from the cathode was a beam of electrons. In CRT TVs and computer monitors, the entire front area of the tube is scanned repeatedly and systematically in a fixed pattern called a raster scan, raster. In color devices, an image is produced by con ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vacuum Fluorescent Display
A vacuum fluorescent display (VFD) is a display device once commonly used on consumer electronics equipment such as video cassette recorders, car audio, car radios, and microwave ovens. A VFD operates on the principle of cathodoluminescence, roughly similar to a cathode-ray tube, but operating at much lower voltages. Each tube in a VFD has a phosphor-coated carbon anode that is bombarded by electrons emitted from the thermionic cathode, cathode filament.Chen, J., Cranton, W., & Fihn, M. (Eds.). (2016). Handbook of Visual Display Technology. doi:10.1007/978-3-319-14346-0 page 1610 onwards In fact, each tube in a VFD is a triode vacuum tube because it also has a mesh control grid. Unlike liquid crystal displays (LCDs), a VFD emits very bright light with high contrast and can support display elements of various colors. Standard illumination figures for VFDs are around 640 Candela per square metre, cd/m2 with high-brightness VFDs operating at 4,000 cd/m2, and experimental un ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fluorescent Labelling
In molecular biology and biotechnology, a fluorescent tag, also known as a fluorescent label or fluorescent probe, is a molecule that is attached chemically to aid in the detection of a biomolecule such as a protein, antibody, or amino acid. Generally, fluorescent tagging, or labeling, uses a reactive derivative of a fluorescent molecule known as a fluorophore. The fluorophore selectively binds to a specific region or functional group on the target molecule and can be attached chemically or biologically. Various labeling techniques such as enzymatic labeling, protein labeling, and genetic labeling are widely utilized. Ethidium bromide, fluorescein and green fluorescent protein are common tags. The most commonly labelled molecules are antibodies, proteins, amino acids and peptides which are then used as specific probes for detection of a particular target. History The development of methods to detect and identify biomolecules has been motivated by the ability to improve the s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
