Nitric acid is not a strong complex former, but it does dissolve many metals, and it forms an impervious passive film on many others.
"He has to show independents, conservative Democrats and moderate Republicans — all of those votes are still up for grabs — that he's still a strong leader," former Gov. Edward G. Rendell of Pennsylvania said in an interview.
Furthermore, in 2013 much of the perennially fragmented opposition had united to form one party, the All Progressives Congress APCC), and the APC chose a strong candidate, former military head of state Muhammadu Buhari, to face Jonathan in the 2015 presidential election.
One wild card is Mr. Erdogan, a strong-willed former Islamist who is the driving force behind Turkey's criticism of Israel and its policy toward the Palestinians.
Underlining the challenge to the country's future, analysts said, is the growing popularity of Milorad Dodik, the Bosnian Serb prime minister, a strong-willed former basketball player who has repeatedly called for the Serbian Republic to secede.
"He is a good man, a strong man," the former officer said.
Gov. Michael F. Easley, a Democrat, fended off a strong challenge from former State Senator Patrick Ballantine.
But this is a strong debut from former documentary-maker Sharon Maguire, who directs with chutzpah and style.
Mr Sanders had a strong lead over former Secretary of State Hillary Clinton, who narrowly beat him in Iowa despite polls showing him with a 2-1 lead.
And my poll-of-polls doesn't really reflect the big story of the past few days: a strong surge by former Pennsylvania Senator Rick Santorum.
