|
Zinc Toxicity
Zinc toxicity is a medical condition involving an overdose on, or toxic overexposure to, zinc. Such toxicity levels have been seen to occur at ingestion of greater than 50 mg of zinc. Excessive absorption of zinc can suppress copper and iron absorption. The free zinc ion in solution is highly toxic to bacteria, plants, invertebrates, and even vertebrate fish. Zinc is an essential trace metal with very low toxicity in humans. Signs and symptoms Following an oral intake of extremely high doses of zinc (where 300 mg Zn/d – 20 times the US Recommended Dietary Allowance, RDA – is a "low intake" overdose), nausea, vomiting, pain, cramps, and diarrhea may occur. There is evidence of induced copper deficiency, alterations of blood lipoprotein levels, increased levels of Low-density lipoprotein, LDL, and decreased levels of High-density lipoprotein, HDL at long-term intakes of 100 mg Zn/d. The USDA Recommended Dietary Allowance, RDA is 15 mg Zn/d. Ther ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Zinc
Zinc is a chemical element with the symbol Zn and atomic number 30. Zinc is a slightly brittle metal at room temperature and has a shiny-greyish appearance when oxidation is removed. It is the first element in group 12 (IIB) of the periodic table. In some respects, zinc is chemically similar to magnesium: both elements exhibit only one normal oxidation state (+2), and the Zn2+ and Mg2+ ions are of similar size.The elements are from different metal groups. See periodic table. Zinc is the 24th most abundant element in Earth's crust and has five stable isotopes. The most common zinc ore is sphalerite (zinc blende), a zinc sulfide mineral. The largest workable lodes are in Australia, Asia, and the United States. Zinc is refined by froth flotation of the ore, roasting, and final extraction using electricity ( electrowinning). Zinc is an essential trace element for humans, animals, plants and for microorganisms and is necessary for prenatal and postnatal development. It ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Galvanize
Galvanization or galvanizing (American and British English spelling differences, also spelled galvanisation or galvanising) is the process of applying a protective zinc coating to steel or iron, to prevent rusting. The most common method is hot-dip galvanization, hot-dip galvanizing, in which the parts are submerged in a bath of hot, molten zinc. Protective action The zinc coating, when intact, prevents corrosive substances from reaching the underlying iron. Additional electroplating such as a chromate conversion coating may be applied to provide further Passivation (chemistry)#Surface passivation, surface passivation to the substrate material. History and etymology The earliest known example of galvanized iron was encountered by Europeans on 17th-century Indian armour in the Royal Armouries Museum collection. The term "galvanized" continues to be used metaphorically of any stimulus which results in activity by a person or group of people. In modern usage, the term "galva ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Polydithiocarbamate Resin
In organic chemistry, a dithiocarbamate is a functional group with the general formula and Chemical structure, structure . It is the analog of a carbamate in which both oxygen atoms are replaced by sulfur atoms (when only 1 oxygen is replaced the result is thiocarbamate). A common example is sodium diethyldithiocarbamate. Dithiocarbamates and their derivatives are widely used in the vulcanization of rubber. Formation Many primary and secondary amines react with carbon disulfide and sodium hydroxide to form dithiocarbamate salts: :R2NH + CS2 + NaOH → R2NCS2−Na+ + H2O Ammonia reacts with CS2 similarly: :2 NH3 + CS2 → H2NCS2−NH4+ Dithiocarbamate salts are pale colored solids that are soluble in water and polar organic solvents. Reactions Dithiocarbamates are readily S-alkylated. Thus, methyl dimethyldithiocarbamate can be prepared by methylation of the dithiocarbamate: :(CH3)2NCS2Na + (CH3O)2SO2 → (CH3)2NC(S)SCH3 + Na[CH3OSO3] Oxidation of dit ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Inductively Coupled Plasma Atomic Emission Spectroscopy
Inductively coupled plasma atomic emission spectroscopy (ICP-AES), also referred to as inductively coupled plasma optical emission spectroscopy (ICP-OES), is an analytical technique used for the detection of chemical elements. It is a type of emission spectroscopy that uses the inductively coupled plasma to produce excited atoms and ions that emit electromagnetic radiation at wavelengths characteristic of a particular element. The plasma is a high temperature source of ionised source gas (often argon). The plasma is sustained and maintained by inductive coupling from cooled electrical coils at megahertz frequencies. The source temperature is in the range from 6000 to 10,000 K. The intensity of the emissions from various wavelengths of light are proportional to the concentrations of the elements within the sample. Mechanism The ICP-AES is composed of two parts: the ICP and the optical spectrometer. The ICP torch consists of 3 concentric quartz glass tubes. The output or "work" coi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Iron
Iron () is a chemical element with symbol Fe (from la, ferrum) and atomic number 26. It is a metal that belongs to the first transition series and group 8 of the periodic table. It is, by mass, the most common element on Earth, right in front of oxygen (32.1% and 30.1%, respectively), forming much of Earth's outer and inner core. It is the fourth most common element in the Earth's crust. In its metallic state, iron is rare in the Earth's crust, limited mainly to deposition by meteorites. Iron ores, by contrast, are among the most abundant in the Earth's crust, although extracting usable metal from them requires kilns or furnaces capable of reaching or higher, about higher than that required to smelt copper. Humans started to master that process in Eurasia during the 2nd millennium BCE and the use of iron tools and weapons began to displace copper alloys, in some regions, only around 1200 BCE. That event is considered the transition from the Bronze Age to the Iron A ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Zinc And The Common Cold
(frequently zinc acetate or zinc gluconate lozenges) are a group of dietary supplements that are commonly used for the treatment of the . The use of zinc supplements at doses in excess of 75 mg/day within 24 hours of the onset of symptoms has been shown to reduce the duration of cold symptoms by about 1 day in adults. Adverse effects with zinc supplements by mouth include bad taste and nausea. The intranasal use of zinc-containing nasal sprays has been associated with the loss of the sense of smell; consequently, in June 2009, the United States Food and Drug Administration (USFDA) warned consumers to stop using intranasal zinc. The human rhinovirus – the most common viral pathogen in humans – is the predominant cause of the common cold. The hypothesized mechanism of action by which zinc reduces the severity and/or duration of cold symptoms is the suppression of nasal inflammation and the direct inhibition of rhinoviral receptor binding and rhin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Zinc Acetate
Zinc acetate is a salt with the formula Zn(CH3CO2)2, which commonly occurs as the dihydrate Zn(CH3CO2)2·2H2O. Both the hydrate and the anhydrous forms are colorless solids that are used as dietary supplements. When used as a food additive, it has the E number E650. Uses Zinc acetate is a component of some medicines, e.g., lozenges for treating the common cold. Zinc acetate can also be used as a dietary supplement. As an oral daily supplement it is used to inhibit the body's absorption of copper as part of the treatment for Wilson's disease. Zinc acetate is also sold as an astringent in the form of an ointment, a topical lotion, or combined with an antibiotic such as erythromycin for the topical treatment of acne. It is commonly sold as a topical anti-itch ointment. Zinc acetate is used as the catalyst for the industrial production of vinyl acetate from acetylene: Approximately 1/3 of the worlds production uses this route, which because it is environmentally messy, is mainly p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Zinc Gluconate
Zinc gluconate is the zinc salt of gluconic acid. It is an ionic compound consisting of two anions of gluconate for each zinc(II) cation. Zinc gluconate is a popular form for the delivery of zinc as a dietary supplement providing 14.35% elemental zinc by weight. Gluconic acid is found naturally, and is industrially made by the fermentation of glucose, typically by ''Aspergillus niger'', but also by other fungi, e.g. ''Penicillium'', or by bacteria, e.g. ''Acetobacter'', ''Pseudomonas'' and ''Gluconobacter''. In its pure form, it is a white to off-white powder. It can also be made by electrolytic oxidation, although this is a more expensive process. The advantages are a lower microbiological profile, and a more complete reaction, yielding a product with a longer shelf life. Zinc gluconate and the common cold Zinc gluconate has been used in lozenges for treating the common cold. However, controlled trials with lozenges which include zinc acetate have found it has the greatest eff ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Welding
Welding is a fabrication (metal), fabrication process that joins materials, usually metals or thermoplastics, by using high heat to melt the parts together and allowing them to cool, causing Fusion welding, fusion. Welding is distinct from lower temperature techniques such as brazing and soldering, which do not melting, melt the base metal (parent metal). In addition to melting the base metal, a filler material is typically added to the joint to form a pool of molten material (the weld pool) that cools to form a joint that, based on weld configuration (butt, full penetration, fillet, etc.), can be stronger than the base material. Pressure may also be used in conjunction with heat or by itself to produce a weld. Welding also requires a form of shield to protect the filler metals or melted metals from being contaminated or Oxidation, oxidized. Many different energy sources can be used for welding, including a gas flame (chemical), an electric arc (electrical), a laser, an electron ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Zinc
Zinc is a chemical element with the symbol Zn and atomic number 30. Zinc is a slightly brittle metal at room temperature and has a shiny-greyish appearance when oxidation is removed. It is the first element in group 12 (IIB) of the periodic table. In some respects, zinc is chemically similar to magnesium: both elements exhibit only one normal oxidation state (+2), and the Zn2+ and Mg2+ ions are of similar size.The elements are from different metal groups. See periodic table. Zinc is the 24th most abundant element in Earth's crust and has five stable isotopes. The most common zinc ore is sphalerite (zinc blende), a zinc sulfide mineral. The largest workable lodes are in Australia, Asia, and the United States. Zinc is refined by froth flotation of the ore, roasting, and final extraction using electricity ( electrowinning). Zinc is an essential trace element for humans, animals, plants and for microorganisms and is necessary for prenatal and postnatal development. It ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Zinc Oxide
Zinc oxide is an inorganic compound with the formula . It is a white powder that is insoluble in water. ZnO is used as an additive in numerous materials and products including cosmetics, food supplements, rubbers, plastics, ceramics, glass, cement, lubricants, paints, ointments, adhesives, sealants, pigments, foods, batteries, ferrites, fire retardants, and first-aid tapes. Although it occurs naturally as the mineral zincite, most zinc oxide is produced synthetically. ZnO is a wide-band gap semiconductor of the II-VI semiconductor group. The native doping of the semiconductor due to oxygen vacancies or zinc interstitials is n-type. Other favorable properties include good transparency, high electron mobility, wide band gap, and strong room-temperature luminescence. Those properties make ZnO valuable for a variety of emerging applications: transparent electrodes in liquid crystal displays, energy-saving or heat-protecting windows, and electronics as thin-film transistors and lig ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Metal Fume Fever
Metal fume fever, also known as brass founders' ague, brass shakes, zinc shakes, galvie flu, galvo poisoning, metal dust fever, welding shivers, or Monday morning fever, is an illness primarily caused by exposure to chemicals such as zinc oxide (ZnO), aluminium oxide (Al2O3), or magnesium oxide (MgO) which are produced as byproducts in the fumes that result when certain metals are heated. Other common sources are fuming silver, gold, platinum, chromium (from stainless steel), nickel, arsenic, manganese, beryllium, cadmium, cobalt, lead, selenium, and zinc. Welders are routinely exposed to the substances that cause metal fume fever from the base metal, plating, or filler. The most common form of exposure among welders occurs when welding galvanized steel, of which zinc is the primary component of the galvanization process. Galvanized metal must be thoroughly cleaned using an angle grinder or other abrasive means to remove the galvanized coating before welding or burning. Brazing and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
