Molecular beam deflection measurements of small iron, cobalt, and nickel clusters show how magnetism develops as the cluster size is increased from several tens to several hundreds of atoms for temperatures between 80 and 1000 K. Ferromagnetism occurs even for the smallest sizes: for clusters with fewer than about 30 atoms the magnetic moments are atomlike; as the size is increased up to 700 atoms, the magnetic moments approach the bulk limit, with oscillations probably caused by surface-induced spin-density waves. The trends are explained in a magnetic shell model. A crystallographic phase transition from high moment to low moment in iron clusters has also been identified.

In 1974, Ashburner and colleagues postulated a model to explain the control of the puffing sequence on Drosophila polytene chromosomes initiated by the molting hormone 20-hydroxyecdysone. This model inspired a generation of molecular biologists to clone and characterize elements of the model, thereby providing insights into the control of gene networks by steroids, diatomic gases, and other small molecules. It led to the first cloning of the EcR subunit of the heterodimeric EcR-USP ecdysone receptor. X-ray diffraction studies of the ligand-binding domain of the receptor are elucidating the specificity of receptor-ecdysteroid interactions, the selectivity of some environmentally friendly insecticides, the evolution of the EcR-USP heterodimer, and indeed Ashburner's classical biochemical evidence for the central role of the ecdysone receptor in his model.

The major postembryonic developmental events happening in insect life, including molting and metamorphosis, are regulated and coordinated temporally by pulses of ecdysone. The biological activity of this steroid hormone is mediated by two nuclear receptors: the ecdysone receptor (EcR) and the Ultraspiracle protein (USP). The crystal structure of the ligand-binding domain from the lepidopteran Heliothis virescens USP reported here shows that the loop connecting helices H1 and H3 precludes the canonical agonist conformation. The key residues that stabilize this unique loop conformation are strictly conserved within the lepidopteran USP family. The presence of an unexpected bound ligand that drives an unusual antagonist conformation confirms the induced-fit mechanism accompanying the ligand binding. The ligand-binding pocket exhibits a retinoid X receptor-like anchoring part near a conserved arginine, which could interact with a USP ligand functional group. The structure of this receptor provides the template for designing inhibitors, which could be utilized as a novel type of environmentally safe insecticides.

Photofragmentation mass spectra of metal–fullerene clusters ${\mathrm{C}}_{\mathrm{60}}{\mathrm{M}}_x$ and ${\mathrm{C}}_{\mathrm{70}}{\mathrm{M}}_x$ $(\mathrm{M=\{Fe,\hspace{0.5em}Co,\hspace{0.5em}Ni,\hspace{0.5em}Rh\}};$ $\text{x=0,…,30)}$ reveal the existence of a reaction channel which yields clusters having the composition ${\mathrm{C}}_{\text{59−2n}}\mathrm{M}$ and ${\mathrm{C}}_{\text{69−2n}}\mathrm{M}$ $\text{(n=0,…,10).}$ Enhanced abundances of clusters with 44, 50, and 60 atoms, as well as the presence of clusters containing almost exclusively an even number of atoms, indicate that one carbon atom of the fullerene cage is replaced by a transition metal atom. Additional tandem time-of-flight (TOF) experiments on mass selected ${\mathrm{C}}_{\mathrm{59}}\mathrm{M}$ and ${\mathrm{C}}_{\mathrm{69}}\mathrm{M}$ indicate that the initial fragmentation step of this new kind of substitutionally doped fullerenes is the loss of a neutral MC molecule. Measurements on preselected ${\mathrm{C}}_{\mathrm{70}}{\mathrm{Rh}}_{\mathrm{3}}$ and ${\mathrm{C}}_{\mathrm{70}}{\mathrm{Ir}}_{\mathrm{2}}$ were performed in order to monitor in detail their laser induced transformation into ${\mathrm{C}}_{\mathrm{69}}\mathrm{Rh}$ and ${\mathrm{C}}_{\mathrm{69}}\mathrm{Ir}.$