>   The journal Applied Sciences (ISSN 2076-3417, IF 2.474) is currently
>   running a Special Issue entitled "The Impact of Artificial Intelligence
>   on Education". Prof. Boris Aber��ek is serving as Guest Editor for this
>   issue.
>   ...
>   Applied Sciences (ISSN 2076-3417; http://www.mdpi.com/journal/applsci)
>   is a journal published by MDPI, Basel, Switzerland.

MDPI was included in Jeffrey Beall'sl list of predatory open access
publishers from 2014 to 2015.  When he was forced by employer pressure
and legal threats to take the list down in 2017, Beall cited MDPI as one
of the publishers pressuring his employer, the University of Colorado
Denver.  A critical view of MDPI can be found here:

  https://www.universityaffairs.ca/features/feature-article/beware-academics-getting-reeled-scam-journals/

Further information on MDPI controversies is available on Wikipedia:

  https://en.wikipedia.org/wiki/MDPI

There are some highly reputable open access publishers, such as PLOS
One.  And there are a lot of disreputable ones.

-- Dave Touretzky