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Phenidone
Phenidone (1-phenyl-3-pyrazolidinone) is an organic compound that is primarily used as a photographic developer. It has five to ten times the developing power as Metol, capable of achieving the same level of development in both less time and at a lower concentration. It also has low toxicity and unlike some other developers, does not cause dermatitis Dermatitis is a term used for different types of skin inflammation, typically characterized by itchiness, redness and a rash. In cases of short duration, there may be small blisters, while in long-term cases the skin may become thickened ... upon skin contact.''Merck Index of Chemicals and Drugs, 9th ed.'' monograph 7115 As a developer, Phenidone is typically used in conjunction with hydroquinone for black and white photography and performs better at lower pH levels. Phenidone is Ilford's trademark for this material, which was first filed on Feb. 24, 1953, but has since expired. Although the compound was first prepared in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Photographic Developer
In the Photographic processing, processing of photographic films, plates or papers, the photographic developer (or just developer) is one or more chemicals that convert the latent image to a visible image. Developing agents achieve this conversion by Redox, reducing the silver halides, which are pale-colored, into silver metal, which is black when in the form of fine particles.Karlheinz Keller et al. ''Photography'' in ''Ullmann's Encyclopedia of Industrial Chemistry'', 2005, Wiley-VCH, Weinheim. . The conversion occurs within the gelatine matrix. The special feature of photography is that the developer acts more quickly on those particles of silver halide that have been exposed to light. When left in developer, all the silver halides will eventually be reduced and turn black. Generally, the longer a developer is allowed to work, the darker the image. Chemical composition of developers The developer typically consists of a mixture of chemical compounds prepared as an aqueous solut ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Metol
Metol is a trade name for the organic compound with the formula OC6H4NH2(CH3)sub>2HSO4. It is the sulfate salt of ''N''-methylaminophenol. This colourless salt is a popular photographic developer used in monochrome photography.Gerd Löbbert "Photography" in Ullmann's Encyclopedia of Industrial Chemistry, 2005, Wiley-VCH, Weinheim. Synthesis and degradation Several methods exist for the preparation of ''N''-methylaminophenol. It arises by decarboxylation of ''N''-4-hydroxyphenylglycine ( Glycin). It can be obtained by reaction of hydroquinone with methylamine. Being an electron-rich arene, metol is readily degraded by hydrogen peroxide. Application Metol is an excellent developing agent for most continuous tone developer applications, and it has been widely used in published developer formulas as well as commercial products. However, it is difficult to produce highly concentrated developer solutions using Metol, and therefore, most Metol developers are supplied in dry chemica ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Organic Compound
Some chemical authorities define an organic compound as a chemical compound that contains a carbon–hydrogen or carbon–carbon bond; others consider an organic compound to be any chemical compound that contains carbon. For example, carbon-containing compounds such as alkanes (e.g. methane ) and its derivatives are universally considered organic, but many others are sometimes considered inorganic, such as certain compounds of carbon with nitrogen and oxygen (e.g. cyanide ion , hydrogen cyanide , chloroformic acid , carbon dioxide , and carbonate ion ). Due to carbon's ability to catenate (form chains with other carbon atoms), millions of organic compounds are known. The study of the properties, reactions, and syntheses of organic compounds comprise the discipline known as organic chemistry. For historical reasons, a few classes of carbon-containing compounds (e.g., carbonate salts and cyanide salts), along with a few other exceptions (e.g., carbon dioxide, and even ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dermatitis
Dermatitis is a term used for different types of skin inflammation, typically characterized by itchiness, redness and a rash. In cases of short duration, there may be small blisters, while in long-term cases the skin may become thickened. The area of skin involved can vary from small to covering the entire body. Dermatitis is also called eczema but the same term is often used for the most common type of skin inflammation, atopic dermatitis. The exact cause of the condition is often unclear. Cases may involve a combination of allergy and poor venous return. The type of dermatitis is generally determined by the person's history and the location of the rash. For example, irritant dermatitis often occurs on the hands of those who frequently get them wet. Allergic contact dermatitis occurs upon exposure to an allergen, causing a hypersensitivity reaction in the skin. Prevention of atopic dermatitis is typically with essential fatty acids, and may be treated with moistu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Redox
Redox ( , , reduction–oxidation or oxidation–reduction) is a type of chemical reaction in which the oxidation states of the reactants change. Oxidation is the loss of electrons or an increase in the oxidation state, while reduction is the gain of electrons or a decrease in the oxidation state. The oxidation and reduction processes occur simultaneously in the chemical reaction. There are two classes of redox reactions: * Electron transfer, Electron-transfer – Only one (usually) electron flows from the atom, ion, or molecule being oxidized to the atom, ion, or molecule that is reduced. This type of redox reaction is often discussed in terms of redox couples and electrode potentials. * Atom transfer – An atom transfers from one Substrate (chemistry), substrate to another. For example, in the rusting of iron, the oxidation state of iron atoms increases as the iron converts to an oxide, and simultaneously, the oxidation state of oxygen decreases as it accepts electrons r ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Arachidonic Acid
Arachidonic acid (AA, sometimes ARA) is a polyunsaturated omega−6 fatty acid 20:4(ω−6), or 20:4(5,8,11,14). It is a precursor in the formation of leukotrienes, prostaglandins, and thromboxanes. Together with omega−3 fatty acids and other omega−6 fatty acids, arachidonic acid provides energy for body functions, contributes to cell membrane structure, and participates in the synthesis of eicosanoids, which have numerous roles in physiology as signaling molecules. Its name derives from the ancient Greek neologism ''arachis'' 'peanut', although peanut oil does not contain any arachidonic acid. Arachidonate is the name of the derived carboxylate anion ( conjugate base of the acid), salts, and some esters. Chemistry In chemical structure, arachidonic acid is a carboxylic acid with a 20-carbon chain and four '' cis''- double bonds; the first double bond is located at the sixth carbon from the omega end. Some chemistry sources define 'arachidonic acid' to designa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Systemic Inflammatory Response Syndrome
In immunology, systemic inflammatory response syndrome (SIRS) is an inflammation, inflammatory state affecting the whole body. It is the body's Immune response, response to an infectious or noninfectious Insult (medical), insult. Although the definition of SIRS refers to it as an "inflammatory" response, it actually has pro- and anti-inflammatory components. Presentation Complications SIRS is frequently complicated by failure of one or more organs or organ systems. The complications of SIRS include * Acute kidney injury * Shock (circulatory), Shock * Multiple organ dysfunction syndrome Causes The causes of SIRS are broadly classified as infectious or noninfectious. Causes of SIRS include: * bacterial infections * severe malaria * Physical trauma, trauma * burn (injury), burns * pancreatitis * ischemia * hemorrhage Other causes include: * Complications of surgery * Adrenal insufficiency * Pulmonary embolism * Complicated aortic aneurysm * Cardiac tamponade * Anaphylaxis * Dru ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phenyl Hydrazine
Phenylhydrazine is the chemical compound with the formula . It is often abbreviated as . It is also found in edible mushrooms. Properties Phenylhydrazine forms monoclinic prisms that melt to an oil around room temperature which may turn yellow to dark red upon exposure to air. Phenylhydrazine is miscible with ethanol, diethyl ether, chloroform and benzene. It is sparingly soluble in water. Preparation Phenylhydrazine is prepared by reacting aniline with sodium nitrite in the presence of hydrogen chloride to form the diazonium salt, which is subsequently reduced using sodium sulfite in the presence of sodium hydroxide to form the final product.''Merck Index of Chemicals and Drugs, 9th ed.'' monograph 7098 History Phenylhydrazine was the first hydrazine derivative characterized, reported by Hermann Emil Fischer in 1875. He prepared it by reduction of a phenyl diazonium salt using sulfite salts. Fischer used phenylhydrazine to characterize sugars via formation of hydrazones ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
3-Chloropropanoic Acid
3-Chloropropanoic acid (also known as 3-chloropropionic acid or UMB66) is the organic compound with the formula ClCH2CH2CO2H. A white or colorless solid, it is used as a drug and a synthetic intermediate. The compound is produced by the hydrochlorination of acrylic acid. In aqueous solution, it has a pKa value of 4.08. This compound is used in scientific research. It is structurally related to GHB and binds to the GHB receptor, but has no affinity for GABA receptors. It is also an active ingredient in some herbicide blends. Overdose may cause unconsciousness or convulsion A convulsion is a medical condition where the body muscles contract and relax rapidly and repeatedly, resulting in uncontrolled shaking. Because epileptic seizures typically include convulsions, the term ''convulsion'' is often used as a synony ...s. It has been demonstrated that the substance can be broken down by both bacteria and fungi as a means of bioremediation. References Convulsants Or ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Photographic Chemicals
Photography is the art, application, and practice of creating images by recording light, either electronically by means of an image sensor, or chemically by means of a light-sensitive material such as photographic film. It is employed in many fields of science, manufacturing (e.g., photolithography), and business, as well as its more direct uses for art, film and video production, recreational purposes, hobby, and mass communication. A person who operates a camera to capture or take photographs is called a photographer, while the captured image, also known as a photograph, is the result produced by the camera. Typically, a lens is used to focus the light reflected or emitted from objects into a real image on the light-sensitive surface inside a camera during a timed exposure. With an electronic image sensor, this produces an electrical charge at each pixel, which is electronically processed and stored in a digital image file for subsequent display or processing. The result w ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
