The pro-fluoride side had more money, more support from officials and more diverse backers, but when the votes were tallied, 60 percent of the city voted against adding fluoride to their water. Fluoride was first added to drinking water in Grand Rapids, Michigan in , just a decade or so after scientists first identified its teeth-saving properties. In , a dentist named Dr. After years of treating patients, McKay figured that the stain must be coming from the water supply they shared. But he also noticed something interesting. People with the brown stains had less tooth decay. In , a chemist with the Aluminum Company of American analyzed the well that the spotted-toothed town drank from and found that the water has high concentrations of fluoride— Enter Dr. In , Grand Rapids began a study to see whether adding fluoride to the water would have the same effect.
Development of radioactive dating methods and their application
The present invention relates to a process for converting a fluoride of a metal to free fluorine gas or to a fluoride of an element other than the metal. Finely ground fluorspar is reacted with con- centrated sulfuric acid to yield hydrogen fluoride. This is dried and then reacted with potassium fluoride to form potassium hydrogen fluoride, KF. Anhydrous potassium hydrogen fluoride is subjected to electrolysis and fluorine gas is obtained at the anode.
At present fluorine is an expensive chemical, particularly when purchased in small quantities. The market for fluorine is large and growing.
Inventor: Kiyohiko Ihara: Fumihiko Yamaguchi: Shinichi Yamane; Current Assignee The present invention relates to a method for producing a fluorine-containing olefin which Publication number Priority date Publication date Assignee Title.
The present invention relates to a fluorine-containing copolymer which has functional groups, and a curable composition containing the copolymer and a curing agent. Conventionally, in room temperature curing fluoro-resin paints which do not require backing at high temperatures upon curing the paints, there has been employed a fluorine-containing copolymer prepared by copolymerizing a fluorolefin, cyclohexyl vinyl ether, and the like as one component of the room temperature curing paints [Japanese Unexamined Patent Publication Tokkyo Kokai Nos.
However, the conventional copolymers have the defect of being poor in compatibility with acrylic resins. The present inventors have found incorporation of acrylic resins into the room temperature curing fluoro-resin paint of the invention improves the weatherability, transparency and pigment dispersibility of the paints. It is an object of the present invention to provide a novel fluorine-containing copolymer having a functional group, which has an excellent transparency and moreover has an excellent compatibility with an acrylic resin.
A further object of the present invention is to provide a curable composition containing the fluorine-containing copolymer and a curing agent. These and other objects of the present invention will become apparent from the description hereinafter. In accordance with the present invention, there is provided a fluorine-containing copolymer comprising structural units of the formula a :. The present invention also provides a curable composition comprising a fluorine-containing copolymer having structural units of the formulas a , b and c and a curing agent.
When the content of the structural units b in the copolymers is from 0.
Facts About Fluorine
Patented Apr. Application July 12, ,. This invention relates to the preparation of fluorine compounds and morev particularly to a method for preparing such compounds by the addition of fluorine to olefinic compounds. Organic fluorine compounds have generally been prepared by the substitutionof chlorine-or bromine by fluorine.
Element Fluorine (F), Group 17, Atomic Number 9, p-block, Mass Sources Fluorine Element – Visual Elements Periodic Table. Discovery date,
Fluorine absorption dating is a method used to determine the amount of time an object has been underground. Fluorine absorption dating can be carried out based on the fact that groundwater contains fluoride ions. Items such as bone that are in the soil will absorb fluoride from the groundwater over time. From the amount of absorbed fluoride in the item, the time that the item has been in the soil can be estimated.
Many instances of this dating method compare the amount of fluorine and uranium in the bones to nitrogen dating to create more accurate estimation of date. Older bones have more fluorine and uranium and less nitrogen. But because decomposition happens at different speeds in different places, it’s not possible to compare bones from different sites. As not all objects absorb fluorine at the same rate, this also undermines the accuracy of such a dating technique. Although this can be compensated for by accommodating for the rate of absorption in calculations, such an accommodation tends to have a rather large margin of error.
In this test was used to easily identify that the ‘ Piltdown Man ‘ was forged, almost 50 years after it was originally ‘unearthed’. From Wikipedia, the free encyclopedia. References [ edit ]. Periods Eras Epochs.
Chemistry History: Teflon & Non-Stick Pans
Remember me. Steinheil, Paris, Davy to E. He was astonished by the analogies between muriatic acid chlorhydric acid and fluoric acid fluorhydric acid and concluded that an element first called oxy-fluoric and then fluorine in French must exist, once he had understood that fluorhydric acid did not contain any oxygen. Among the letters that he exchanged with Davy during the war raging between their two nations, he even suggested on 1st November the possibility of isolating the element fluorine through the electrolysis of anhydrous fluorhydric acid .
The isolation of this new element continued to occupy many researchers for most of the nineteenth century.
Relative dating of archaeological bones by the measurement of fluorine, uranium, and nitrogen content that have been made at the beginning of 20th century.
The invention belongs to chemical industry and field of metallurgy, be specifically related to a kind of side reclaiming Fluohydric acid. Fluohydric acid. Use Usually containing the impurity such as hexafluosilicic acid, fluorine ferrous acid, fluotitanic acid in the hydrofluoric acid waste liquid crossed, people are to reclaiming Fluohydric acid. Bureau The concentrated sulphuric acid decomposition method etc. Lime dinas method: be first Calx, Silicon stone and hexafluosilicic acid to be mixed by a certain percentage.
Generate calcium fluoride and precipitated silica Through filtering and pelletize, it is then sent to the rotary kiln of DEG C. Sodium bifluoride through filtration and sends into reactor DEG C after drying, There is dissociated into sodium fluoride and fluohydric acid gas.
Fluorine absorption dating
Context – Food and drinking water typically contain at least small amounts of fluorides. They occur in the environment both naturally and as a result of human activities. Fluorides are commonly added to dental products — and sometimes to tap water — to prevent cavities. Only inorganic fluorides are the focus of this study, particularly those which are most present in the environment and may affect living organisms. Fluorides are important industrial chemicals with a number of uses but the largest uses are for aluminium production, drinking water fluoridation, and the manufacture of fluoridated dental preparations.
Fluoride concentration in food can be increased by the presence of fluoride in water used for its preparation.
Who Invented Fluorine Dating. Item the in fluoride absorbed of amount the From underground, been has object an time of amount the determine to used method.
This invention relates to a novel curable composition consisting essentially of a fluorine rubber and an amino acid. The fluorine rubber is well known, and finds a wide range of applications because of its superior thermal stability and outstanding resistances to chemicals and oils. Organic peroxides such as dicumyl peroxide, polyamines such as triethylene tetramine, and polyisocyanates are among known vulcanizing agents for fluorine rubbers.
The present inventor has now found that specific amino acids are new and useful vulcanizing agents for fluorine rubbers. The present invention thus provides a curable composition consisting essentially of a fluorine rubber and at least one amino acid selected from the group consisting of arginine, lysine, ornithine, hydroxylysine, glutamine, cystine, asparagine and citrulline.
The accompanying drawing shows the cure curves of compositions illustrated in Example to be given hereinbelow. Various types of fluorine rubbers are known, and for example, vinylidene fluoride-type fluorine rubbers, fluorinated silicone-type fluorine rubbers, fluorinated nitroso-type fluorine rubbers, fluorinated acrylate-type fluorine rubbers, fluorinated polyester-type fluorine rubbers, fluorinated vinyl ether-type fluorine rubbers, fluorinated triazine-type and fluorinated phosphonitrile-type fluorine rubbers are commercially available.
Suitable fluorine rubbers for use in the composition of this invention are the vinylidene fluoride-type, fluorinated nitroso-type and fluorinated acrylate-type fluorine rubbers.
International Bamboo and Rattan Organisation
Application May 24, , Serial No. Thematerials of the, present invention are unique in that they contain,. Though their exact formula is not known, they can be expressed generally by the: empirical formula in which a is 0. In obtaining this general formula, which is based on analysis of the iron-fluorine compositions, b was arbitrarily selected as equal to one. The compounds are prepared by reacting an aqueous solution of hydrogen fluoride with ferrous carbonate, siderite. The reaction is preferably carried out in an iron reactor though a copper reactor may be used if desired or the reactor may be.
Fluoride is the name given to a group of compounds that are composed of the naturally occurring element fluorine and one or more other.
In its fluoride form, it’s a mineral with anti-acid properties used in toothpaste and drinking water to prevent dental cavities. This small, non-toxic element is also widely used by medicinal chemists in cancer treatment, antibiotics, anti-depressants, steroids and other drugs. Fluorine is prevalent in modern drugs because it stabilizes drugs and improves their biological activity.
For many years, researchers in the UTSA Metalloprotein Research Laboratory, led by Aimin Liu, a Lutcher Brown Distinguished Professor, have been studying the regulation of thiols, compounds that affect a variety of biological functions in mammals such as redox stress levels, energy balance, cellular signaling, heart health, and autoimmune and neurological conditions.
When thiol levels are stable, individuals are generally healthy.
Dentists Discovered the Tooth-Saving Properties of Fluoride by Accident
Allotropes Some elements exist in several different structural forms, called allotropes. Each allotrope has different physical properties. For more information on the Visual Elements image see the Uses and properties section below. Group A vertical column in the periodic table. Members of a group typically have similar properties and electron configurations in their outer shell.
In archaeology, geochronology lays the foundations for the dating technique that of obsidian hydration (rind) dating, developed in by Irving Friedman and gain fluorine and uranium at the same rate, an archaeologist can used this as.
The most reactive element on the Periodic Table, fluorine has a violent history in the quest for its discovery. Despite the difficult and sometimes explosive properties of fluorine, it is a vital element for humans and animals, which is why it is commonly found in drinking water and toothpaste. Early chemists tried for years to isolate the element from various fluorides. However, fluorine does not occur free in nature and no chemical substance is capable of freeing fluorine from any of its compounds due to its reactive nature.
For centuries, the mineral fluorspar was used in metal refining. Known today as calcium fluoride CaF 2 , it was used as a flux to separate pure metal from the unwanted minerals in ore, according to Chemicool. The “fluor” comes from the Latin word “fluere,” meaning “to flow,” because that’s what fluorspar allowed metals to do. The mineral was also called Bohemian emerald and was used in glass etching, according to the Jefferson Laboratory.
Many scientists over the decades attempted to experiment with fluorspar to better learn its properties, as well as its composition.