Who am I ? asks a very famous bright yellow powder from WWII

OK, Manhattan : Who am I ????

(a) In the popular imagination, I am often thought of as being a bright yellow powder (though if fact I might often be dark red or brown or even some other color).

(b) Oddly enough, it is exactly the same for me.

(a)  Some of my most important developments happened on Manhattan island, with strong Canadian involvement --- I think that was all about the word "Hope".

(b) Wow ! Me ditto,ditto,ditto !

(a) The international visual symbol for me is characters in dense black type on a bright yellow background.

(b) That's me too .

(a) A large sample of Americans (men mostly) voted me the top news story of the 20th century for the Newseum.

(b) A large sample of Americans (women mostly) also voted me the top news story of the century for the Newseum.

(a) A little boy is the dramatic climax of my story.

(b) Strange, a baby girl is the dramatic climax of my story as well.

(a) Much of my story happened on a campus at Columbia university and involved Columbia university professors.

(b) So did my story !

(a) I was top secret through most of WWII and I was regarded as one of the best Allied military weapons of the war.

(b) What can I say : ditto ditto .

(a) I am regarded as one of the top scientific discoveries to come out of WWII.

(a) Yeah ? Well so am I .

(a) I was a big project for the OSRD, who spent a fortune on me, until another government agency took me over : but the bosses at the OSRD still kept their hand in.

(b) The OSRD spent quite a bundle on me too - still kept doing so, even after I was taken over by another government agency.

(a) Oh yeah, well I was so important that I was flown all over the world in big bombers.

(b) Bet you weren't flown about as much as me in big bombers.

(a) I was a big deal in Britain : they even act like they invented me.

(b), Oh boy, don't I know that feeling.

(a) The British chemical giant, ICL looked for a while like it would be running me but Vannevar Bush of the OSRD soon stopped that.

(b) And that goes for me too.

(a) In my natural state, I hardly seem to exist, consisting of less than 1% of the natural mix.

(b) I know the feeling, too, actually being much less than 1% of the natural mix.

(a) Well I am so similar to others in the mix, at least in conventional chemical terms, that its a life's work to separate me from them.

(b) That's what all the chemists say about me - usually with a very deep sigh.

(a) I won't work at all, unless I am separated from my natural mix and am about 88% pure.

(b) Now there we finally do differ : because I still work perfectly well even if I am only one part in million of the original natural mix.

(a) There was (and is) a tremendous moral row over whether I should have been built at all but none whatsoever about all the money and effort spent on separating me from my natural mix.

(b) Odd, because while there is no debate at all about whether I should have been built, there is a serious moral debate underway about whether so much scarce wartime energy and resources should have been spent on separating me from my natural mix.

 (a) I am considered one of the biggest killing machines in history.

(b) Boy or girl, do we ever part company there : I am one of the smallest lifesavers ever, and one of the best too.

Can you answer this puzzler ?

(a) and (b)  So, dear reader : Who am I ? Who am I ?

Answer : (a) the U-235 in the Little Boy Bomb  (b) an early vial of Penicillin, who baby Patty Malone and  teenagerAnne Shirley Carter helped make an overnight world sensation in August-September 1943 .....