Challenges — Open Access JournalChallenges (ISSN 2078-1547), a scientific open access journal for research proposals and open problems is published online by MDPI biannually.
Forthcoming Special IssuesChallenges in Alternative Energy (Guest Editor: Daniel Kammen)
Challenges to Safety in the Global Drug Supply Chain (Guest Editors: Bryan Liang, Timothy Mackey)
Electronic Waste — Impact, Policy and Green Design (Guest Editors: William Bullock, Joy Scrogum)
Food Security (Guest Editor: Michael Winter)
Water Quality in the City (Guest Editor: Andy James)