The lanthanides obey the Oddo-Harkins rule — odd-numbered elements are less abundant than their even-numbered neighbors. Three of the lanthanide elements have radioactive isotopes with long half-lives La, Sm and Lu that can be used to date minerals and rocks from Earth, the Moon and meteorites. Lanthanide elements and their compounds have many uses but the quantities consumed are relatively small in comparison to other elements. From the perspective of value, however, applications in phosphors and magnets are more important. The devices lanthanide elements are used in include superconductors , samarium-cobalt and neodymium-iron-boron high-flux rare-earth magnets , magnesium alloys, electronic polishers, refining catalysts and hybrid car components primarily batteries and magnets.
Erbium-doped fiber amplifiers are significant devices in optical-fiber communication systems. Phosphors with lanthanide dopants are also widely used in cathode ray tube technology such as television sets. The earliest color television CRTs had a poor-quality red; europium as a phosphor dopant made good red phosphors possible.
Yttrium iron garnet YIG spheres can act as tunable microwave resonators. Lanthanide oxides are mixed with tungsten to improve their high temperature properties for TIG welding , replacing thorium , which was mildly hazardous to work with. Many defense-related products also use lanthanide elements such as night vision goggles and rangefinders.
The SPY-1 radar used in some Aegis equipped warships, and the hybrid propulsion system of Arleigh Burke -class destroyers all use rare earth magnets in critical capacities. Most lanthanides are widely used in lasers , and as co- dopants in doped-fiber optical amplifiers; for example, in Er-doped fiber amplifiers, which are used as repeaters in the terrestrial and submarine fiber-optic transmission links that carry internet traffic.
These elements deflect ultraviolet and infrared radiation and are commonly used in the production of sunglass lenses. Other applications are summarized in the following table: . As mentioned in the industrial applications section above, lanthanide metals are particularly useful in technologies that take advantage of their reactivity to specific wavelengths of light. These are well-suited for this application due to their large Stokes shifts and extremely long emission lifetimes from microseconds to milliseconds compared to more traditional fluorophores e.
The biological fluids or serum commonly used in these research applications contain many compounds and proteins which are naturally fluorescent. Therefore, the use of conventional, steady-state fluorescence measurement presents serious limitations in assay sensitivity. Long-lived fluorophores, such as lanthanides, combined with time-resolved detection a delay between excitation and emission detection minimizes prompt fluorescence interference. This method involves two fluorophores: a donor and an acceptor. Excitation of the donor fluorophore in this case, the lanthanide ion complex by an energy source e.
The acceptor fluorophore in turn emits light at its characteristic wavelength. The two most commonly used lanthanides in life science assays are shown below along with their corresponding acceptor dye as well as their excitation and emission wavelengths and resultant Stokes shift separation of excitation and emission wavelengths. Currently there is research showing that lanthanide elements can be used as anticancer agents.
The main role of the lanthanides in these studies is to inhibit proliferation of the cancer cells. Specifically cerium and lanthanum have been studied for their role as anti-cancer agents. One of the specific elements from the lanthanide group that has been tested and used is cerium Ce. There have been studies that use a protein-cerium complex to observe the effect of cerium on the cancer cells.
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The hope was to inhibit cell proliferation and promote cytotoxicity. Transferrin acts as a growth factor for the cancerous cells and is dependent on iron.
Cancer cells have much higher levels of transferrin receptors than normal cells and are very dependent on iron for their proliferation. Cerium may bind in the place of iron on to the transferrin and then be brought into the cancer cells by transferrin-receptor mediated endocytosis. This creates a toxic environment for the cancer cells and causes a decrease in cell growth.
This is the proposed mechanism for cerium's effect on cancer cells, though the real mechanism may be more complex in how cerium inhibits cancer cell proliferation. Specifically in HeLa cancer cells studied in vitro, cell viability was decreased after 48 to 72 hours of cerium treatments. Cells treated with just cerium had decreases in cell viability, but cells treated with both cerium and transferrin had more significant inhibition for cellular activity. Another specific element that has been tested and used as an anti-cancer agent is lanthanum, more specifically lanthanum chloride LaCl 3.
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The lanthanum ion is used to affect the levels of let-7a and microRNAs miRa in a cell throughout the cell cycle. When the lanthanum ion was introduced to the cell in vivo or in vitro, it inhibited the rapid growth and induced apoptosis of the cancer cells specifically cervical cancer cells. This effect was caused by the regulation of the let-7a and microRNAs by the lanthanum ions.
Due to their sparse distribution in the earth's crust and low aqueous solubility, the lanthanides have a low availability in the biosphere, and for a long time were not known to naturally form part of any biological molecules. In a novel methanol dehydrogenase that strictly uses lanthanides as enzymatic cofactors was discovered in a bacterium from the phylum Verrucomicrobia , Methylacidiphilum fumariolicum.
This bacterium was found to survive only if there are lanthanides present in the environment. From Wikipedia, the free encyclopedia. Lanthanides in the periodic table. Periodic table forms. Periodic table history. Dmitri Mendeleev predictions. Sets of elements. By periodic table structure. Groups 1— By metallic classification. By other characteristics. Coinage metals Platinum-group metals.
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List of chemical elements. Properties of elements.
Atomic weight Crystal structure. Data pages for elements. In the older literature, the name "lanthanon" was often used. Chemistry International.
Archived from the original on Retrieved 23 March Retrieved on Chemistry of the Elements 2nd ed. Chemistry of the f-block elements. CRC Press. Journal of Chemical Education. Bibcode : JChEd.. Lanthanide and Actinide Chemistry. Encyclopedia of Inorganic and Bioinorganic Chemistry. Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. Angewandte Chemie International Edition in English. WebElements Ltd, UK. Retrieved Journal of the American Chemical Society. Chemical Reviews. Accounts of Chemical Research. Angewandte Chemie International Edition.