Thermo Fisher Scientific has agreed to buy the lab chemicals maker Alfa Aesar for $405 million. Alfa Aesar, owned by catalyst expert Johnson Matthey, had sales of $125 million in 2014 and employs 480 people. Thermo Fisher says the acquisition enhances its portfolio of solvents and reagents. The purchase comes on the heels of another lab chemicals deal, Merck KGaA’s acquisition of Sigma-Aldrich for $17 billion. In that case, the European Commission is requiring Merck to divest some of Sigma’s operations, making additional lab chemicals businesses available to other buyers.