\documentclass{article}
\usepackage[default]{lato}
\usepackage{natbib}
\usepackage {amsmath,amssymb,bm}
\usepackage[scale=1.15]{iwonamath}
\DefineIwonaMathVersion{name=iwonacondensed, condensed}
\DefineIwonaMathVersion{name=iwonalight, light}
\DefineIwonaMathVersion{name=iwonalightcondensed, light, condensed}
\newcommand\ibinom[2]{\genfrac\lbrace\rbrace{0pt}{}{#1}{#2}} 
\long\def\sample{%
  First some large operators both in text:
\smash{$ \iiint\limits_{\mathcal{Q}} f(x,y,z)\,dx\,dy\,dz $}
and
$\prod_{\gamma\in\Gamma_{\widetilde{C}}} \partial(\widetilde{X}_\gamma)$;
and also on display:

\begin{equation}
\begin{split}
\iiiint\limits_{\mathbf{Q}} f(w,x,y,z)\,dw\,dx\,dy\,dz  &\leq
\oint_{\bm{\partial Q}} f' \left( \max \left\lbrace
\frac{\lVert w \rVert}{\lvert w^2 + x^2 \rvert} ;
\frac{\lVert z \rVert}{\lvert y^2 + z^2 \rvert} ;
\frac{\lVert w \oplus z \rVert}{\lVert x \oplus y \rVert}
\right\rbrace\right)
\\
&\precapprox \biguplus_{\mathbb{Q} \Subset \bar{\mathbf{Q}}}
  \left[ f^{\ast} \left(
    \frac{\left\lmoustache\mathbb{Q}(t)\right\rmoustache}
         {\sqrt {1 - t^2}}
  \right)\right]_{t=\alpha}^{t=\vartheta}
  - ( \Delta + \nu - v )^3
\end{split}
\end{equation}

For $x$ in the open interval $ \left] -1, 1 \right[ $
the infinite sum in Equation~\eqref{eq:binom1} is convergent;
however, this does not hold
throughout the closed interval $ \left[ -1, 1 \right] $.
\begin{align}
  (1 - x)^{-k} &=
   1 + \sum_{j=1}^{\infty} (-1)^j \ibinom{k}{j} x^j
    \text{\quad for $k \in \mathbb{N}$; $k \neq 0$.}
    \label{eq:binom1}
\end{align}}


\begin{document}

In this sample we use Lato font~\citep{lato} as the body font.  For the math we
use the same input as in The \LaTeX\ Companion~\citep[\S~12.5]{TLC3}).


In all examples we use Iwona scaled 1.15

\section*{Iwona regular}

\sample

\section*{Iwona condensed}

\mathversion{iwonacondensed}
\sample

\section*{Iwona light}

\mathversion{iwonalight}
\sample

\section*{Iwona light condensed}

\mathversion{iwonalightcondensed}
\sample



\bibliography{iwonamath}
\bibliographystyle{plainnat}

\end{document}