What are metal-organic frameworks and their applications?

The price of gold has hit a record high of more than $4,000 an ounce as investors look for safe places to put their money over concerns about economic and political uncertainty around the world.

Also in the programme: Is time running out for France's President Emmanuel Macron? And we meet the woman trying to become the first person on record to walk the length of Saudi Arabia, from north to south.

(Photo: Gold bars at bullion house in Mumbai. Credit: Reuters/Arko Datta/File Photo)