Xuxos for breakfast

XuixoI have just got back from a meeting in Barcelona. My hotel was just round the corner from a local bakery. I got in the habit of having a cafe solo (Spanish espresso), orange juice, water (it was 30+C and very humid at midday), and a xuxo for breakfast. Xuxo is pronounced approximately shooshoo, and is the Catalan version of a donut. They are not donut shaped (see a picture of one above), they are essentially a helix of pastry, deep filled and filled with custard. The bakery’s (‘Rambla 31’) xuxos were lovely.

Anyway, I needed to be fortified by xuxos. The conference schedule was punishing. 8:30 am starts, and on one night, an 8:30 pm finish. Phew. My talk was at 8 pm. At the beginning of the talk, I thanked and praised the audience for their stamina.

It was a big meeting, about 750 people. It was good to meet and talk science with old friends, and to make new friends. I spent a fair bit of time, at the coffee breaks and in chats in the coffee shop/bar on campus, talking to people about a slightly odd, and poorly understood phenomenon, in solutions of calcium carbonate in water. In these solutions, crystals of calcium carbonate should form, but this can take hours or days, in the mean time spheres of size anything up to 100 nanometres or more form. There is an image of these spheres on Fiona Meldrum’s group’s website.

I think these spheres may be of what many people, including many at the conference, would call a gel. A gel is a type of soft solid, that contains water (or another solvent). A jelly (if you want to be a bit more classy and adult, then so are panna cottas) is a gel. It is a solid (just about) but is mostly water. It is a solid because of interlocking strands of gelatin. I think this funny state of calcium carbonate is a solid because of strands/sheets of calcium carbonate.

Many of the people at the meeting work on gels and similar stuff, so I spent some time seeing if I could learn useful stuff from that could be applied to calcium carbonate, on the grounds that it is a lot easier to borrow ideas from others than it is to try and reinvent the wheel.