Damjan and I traveled to Belgrade to give a presentation on Black Carbon and the Aethalometer. About 80 people were in attendance, and it was probably the largest audience I have had for a talk like this. Belgrade is a very interesting and beautiful city, the point where the Sava and Danube rivers meet. On the way back from Serbia we got stopped at the Croatian / Slovene Border because of a small problem at Customs which cost us ~150 euros and 3 hours of our time. It was a really long day.