The thermal decomposition of ammonium paratungstate tetrahydrate (APT·4H2O), (NH4)10[H2W12O42]·4H2O, in air to tungsten trioxide, WO3, was investigated under non-isothermal conditions using thermal analysis coupled on-line by a Skimmer® system to a quadrupole mass spectrometer (TA-MS) for evolved gas analysis (EGA), with X-ray powder diffraction (XRD), with Fourier

Tungsten has a rich history dating back to its discovery during the 18th century. Peter Woulfe was the first to recognize a new element in the naturally occurring mineral wolframite. Tungsten was originally known as wolfram, explaining the choice of "W" for its elemental symbol. Swedish chemist Carl Wilhelm Scheele contributed to its discovery as well with his studies on the mineral scheelite.

In 1841, a chemist named Robert Oxland gave the first procedures for preparing tungsten trioxide and sodium tungstate.He was granted patents for his work soon after, and is considered to be the founder of systematic tungsten chemistry.

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Several techniques have been used to study the structure of the Keggin-type polyoxometalate salt ammonium metatungstate(AMT)—(NH4)6[H2W12O40]*nH2O, a potential fuel cell catalyst. The dehydrated salt is comprised of a mixture of crystallites of different unit cells in a centered eutactic cubic configuration, with an average unit cell of a≅12.295. Varied orientations of the Keggin ions in the cubic arrangement create the differences, and orientational variation within each unit cell size represents an energy well.

Using a coupling process of neutralization–nanofiltration–crystallization, pure  is producted . The effects of chemical neutralization of ammonium paratungstate (APT) by nitric acid, operating pressure, the concentration of AMT and the volume of washing water on the coupling process were systematically discussed. It was found that the better conditions of AMT

The thermal decomposition of ammoniu metatungstate(AMT)involved several steps in inert atmosphere: (i)That is release of crystal water between 25°C and 200°C resulte in dehydrated AMT. (ii) The formation of an amorphous phase between 200°C and 380 °C.

The structure of ammonium metatungstate powder is highly dependent on hydration and POM molecule rotation, with cation and hydrogen  bonding  forces directing  a  mixture  of structure that have been studied with bulk and single-crystal  methods.   The illustration show simulated anion structural disorder that the fully dehydrated form of the  compound.

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The dartboard may have its origins in the cross-section of a tree. An old name for a dartboard is "butt"; the word comes from the French word , but the meaning is "target". In particular, the Yorkshire and Manchester Log End boards are differ from the standard board in that they have no treble, only double and bulls’ eye, the Manchester board being of a smaller diameter, with a playing area of only 25 cm across with double and bull areas measuring just 4mm. The London Fives board is another variation. This has only 12 equal segments numbered 20, 5, 15, 10, 20, 5, 15, 10, 20, 5, 15, 10 with the doubles and triples being a quarter of an inch wide.

There is a speculation that the game originated among soldiers throwing short arrows at the bottom of the cask or at the bottom of trunks of trees. As the wood dried, cracks would develop, creating "sections". Soon, regional standards emerged and many woodworkers supplemented bar tabs by fabricating dart boards for the local pubs.

The standard numbering plan with a 20 on top was created in 1896 by Lancashire carpenter Brian Gamlin. However, a great many other configurations have been used throughout the years and in different geographical locations. Gamlin's layout was devised to penalize inaccuracy. Although the most of the boards, the left-hand side (near the 14 section) is preferred by beginners, for its concentration of larger numbers. Mathematically, removing the rotational symmetry by placing the "20" at the top, there are 19!, or 121,645,100,408,832,000 possible dartboards. Many different layouts would penalize a player more than the current setup, however, the current setup actually does the job rather efficiently. There have been several mathematical papers published that consider the "optimal" dartboard.

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