Zeolites are microporous, aluminosilicate minerals used as commercial adsorbents and catalysts. The term zeolite was coined in 1756 by Swedish mineralogist Axel Fredrik Cronstedt, who observed that heating the material, believed to have been stilbite, produced large amounts of steam from water, adsorbed by the material. Based on this, he called the material zeolite, from the Greek ζέω, meaning "to boil" and λίθος, meaning "stone"; the classic reference for the field has been Breck's book Zeolite Molecular Sieves: Structure, And Use. Zeolites occur but are produced industrially on a large scale; as of December 2018, 245 unique zeolite frameworks have been identified, over 40 occurring zeolite frameworks are known. Every new zeolite structure, obtained is examined by the International Zeolite Association Structure Commission and receives a three letter designation. Zeolites have a porous structure that can accommodate a wide variety of cations, such as Na+, K+, Ca2+, Mg2+ and others; these positive ions are rather loosely held and can be exchanged for others in a contact solution.
Some of the more common mineral zeolites are analcime, clinoptilolite, natrolite and stilbite. An example of the mineral formula of a zeolite is: Na2Al2Si3O10 the formula for natrolite; these cation exchanged. Natural zeolites form. Zeolites crystallize in post-depositional environments over periods ranging from thousands to millions of years in shallow marine basins. Occurring zeolites are pure and are contaminated to varying degrees by other minerals, quartz, or other zeolites. For this reason occurring zeolites are excluded from many important commercial applications where uniformity and purity are essential. Zeolites are the aluminosilicate members of the family of microporous solids known as "molecular sieves", consist of Si, Al, O, metals including Ti, Sn, Zn, so on; the term molecular sieve refers to a particular property of these materials, i.e. the ability to selectively sort molecules based on a size exclusion process. This is due to a regular pore structure of molecular dimensions; the maximum size of the molecular or ionic species that can enter the pores of a zeolite is controlled by the dimensions of the channels.
These are conventionally defined by the ring size of the aperture, for example, the term "8-ring" refers to a closed loop, built from eight tetrahedrally coordinated silicon atoms and 8 oxygen atoms. These rings are not always symmetrical due to a variety of causes, including strain induced by the bonding between units that are needed to produce the overall structure, or coordination of some of the oxygen atoms of the rings to cations within the structure. Therefore, the pores in many zeolites are not cylindrical. Zeolites transform to other minerals under weathering, hydrothermal alteration or metamorphic conditions; some examples: The sequence of silica-rich volcanic rocks progresses from: Clay → quartz → mordenite–heulandite → epistilbite → stilbite → thomsonite–mesolite-scolecite → chabazite → calcite. The sequence of silica-poor volcanic rocks progresses from: Cowlesite → levyne–offretite → analcime → thomsonite–mesolite-scolecite → chabazite → calcite. Industrially important zeolites are produced synthetically.
Typical procedures entail heating aqueous solutions of silica with sodium hydroxide. Equivalent reagents include sodium silicate. Further variations include changes in the cations to include quaternary ammonium cations. Synthetic zeolites hold some key advantages over their natural analogues; the synthetic materials are manufactured in a phase-pure state. It is possible to produce zeolite structures that do not appear in nature. Zeolite A is a well-known example. Since the principal raw materials used to manufacture zeolites are silica and alumina, which are among the most abundant mineral components on earth, the potential to supply zeolites is unlimited. Conventional open-pit mining techniques are used to mine natural zeolites; the overburden is removed to allow access to the ore. The ore may be blasted or stripped for processing by using tractors equipped with ripper blades and front-end loaders. In processing, the ore is crushed and milled; the milled ore may be shipped in bags or bulk. The crushed product may be screened to remove fine material when a granular product is required, some pelletized products are produced from fine material.
As of 2016 the world's annual production of natural zeolite approximates 3 million tonnes. Major producers in 2010 included China, South Korea, Jordan, Turkey Slovakia and the United States; the ready availability of zeolite-rich rock at low cost and the shortage of competing minerals and rocks are the most important factors for its large-scale use. According to the United States Geological Survey, it is that a significant percentage of the material sold as zeolites in some countries is ground or sawn volcanic tuff that contains only a small amount of zeolites; some examples of such usage include dimension stone, lightweight aggregate, pozzolanic cement, soil con
Angels Cry is the debut album of Brazilian metal band Angra. It was recorded in Germany at Kai Hansen's studios in Hamburg; the opening track is a short rendition of the first movement of Franz Schubert's "Symphony No. 8" known as his "Unfinished Symphony". In addition, the title track features a brief arrangement of "Caprice no. 24" by Niccolò Paganini, whereas "Evil Warning" features a brief arrangement of "Winter" by Antonio Vivaldi. The opening of the track "Never Understand" features a brief arrangement of the song "Asa Branca" by Luiz Gonzaga; the opening section of the closing track "Lasting Child", entitled "The Parting Words", is an adaptation of the theme of Felix Mendelssohn's "Variations sérieuses", Op. 54. When commenting on the production and recording of the album, vocalist Andre Matos said that recording the album was difficult due to the inexperience of him and his bandmates, due to the difference of musical influences between them and the producers, he referred to the recording as "an exile": Producer Charlie Bauerfeind was not confident that drummer and co-founder Marcos Antunes would be skillful enough for the music he expected to put in the album, so he told the band they could either fire him and hire Alex Holzwarth as a session musician or use electronic drums - or otherwise he would leave the project.
The band decided to do as he said and replaced Antunes with Holzwarth, a decision Matos regards as being difficult. One of the songs, was performed by a different drummer: Kate Bush cover "Wuthering Heights", played by Gamma Ray drummer Thomas Nack. Matos said Nack was a big fan of Bush and "could play those lines perfectly"; the inlays and photo shoots for the album display drummer Ricardo Confessori, but he would only join the band after its recording. Antunes appears on the back sleeve and inlays of the Japanese first press of the album instead of Confessori. All lyrics are written by Andre Matos except Stand Away by Rafael Bittencourt and Wuthering Heights by Kate Bush. André Matos – lead vocals, piano Kiko Loureiro – lead and rhythm guitars Rafael Bittencourt – rhythm and lead guitars Luís Mariutti - bass guitar Alex Holzwarth – drums, percussion except in Track #7 Dirk Schlächter – lead guitar in Track #6 Kai Hansen – lead guitar in Track #6 Sascha Paeth – acoustic and lead guitars in Track #6 Thomas Nack – drums in track #7
A general election will be held in the U. S. state of Connecticut on November 4, 2014. All of Connecticut's executive officers are up for election as well as all of Connecticut's five seats in the United States House of Representatives. Primary elections were held on August 26, 2014. Incumbent Democratic Governor Dannel Malloy and Lieutenant Governor Nancy Wyman are running for re-election to a second term in office; the Republican nominees are former U. S. Ambassador to Ireland and nominee for governor in 2010 Thomas C. Foley and Groton Town Councilor Heather Bond Somers. Incumbent Democratic Attorney General George Jepsen is running for re-election to a second term in office; the Republican nominee is attorney and candidate for the U. S. Senate in 2012 Kie Westby. Running is Stephen Fournier of the Green Party, an attorney and former member of the Hartford Board of Education, his party's nominee for Connecticut's 1st congressional district in 2008 and for attorney general in 2010. Incumbent Democratic Secretary of the State Denise Merrill is running for re-election to a second term in office.
The Republican nominee is Peter Lumaj, an Albanian-born attorney and candidate for the U. S. Senate in 2012. Running is Mike DeRosa of the Green Party, a perennial candidate for public office. Incumbent Democratic State Treasurer Denise L. Nappier is running for re-election to a fifth term in office; the Republican nominee is an attorney and the Trumbull Town First Selectman. Financier, movie producer and political activist Bob Eick had been running for the Republican nomination. At the Republican State Convention on May 17, Herbst won the endorsement with 70.3% of the vote to Eick's 29.6%. Despite Eick having polled enough votes to appear on the primary ballot, he withdrew and did not force a primary election. Rolf Maurer of the Green Party, a perennial candidate for public office, is running a write-in campaign, he is the Green Party nominee for comptroller. Incumbent Democratic State Comptroller Kevin Lembo is running for re-election to a second term in office. Two Republicans ran for their party's nomination: Marine Corps veteran and former Republican legislative intern Angel Cadena and accountant Sharon J. McLaughlin.
At the Republican State Convention on May 17, McLaughlin won the endorsement with 63.8% of the vote. Cadena received 36.1 %. Running is Rolf Maurer of the Green Party, a perennial candidate for public office, running a write-in campaign for treasurer. All of Connecticut's five seats in the United States House of Representatives will be up for election in 2014