This is a test article 

$$S(f)(t)=a_{0}+\sum{n=1}{+\infty}{a_{n} \cos(n \omega t)+b_{n} \sin(n \omega t)}$$


and


$$
\begin{aligned}
abc &= def \\
abc &= def
\end{aligned}
$$


<chem>CO2 + C -> 2 CO</chem>

<chem>Hg^2+ ->[I-] HgI2 ->[I-] [Hg^{II}I4]^2-</chem>

<chem>H2O</chem>

<chem>Y^99+</chem>

<chem>^{227}_{90}Th+</chem>

<chem>A <=>> B</chem>