Angular momentum projection from non-axial intrinsic states in Si

States of definite angular momentum projected from seven Hartree-Fock solution of ²⁸Si are used as a basis in which to diagonalize the Hamiltonian. It is found that each of these HF solutions contributes appreciably to the low energy spectrum.     

Reversible Magnetic Agglomeration: A Mechanism for Thermodynamic Control over Nanoparticle Size

We present a method for the synthesis and precise size control of magnetic nanoparticles in a reversible magnetic agglomeration mechanism. In this approach, nanoparticles nucleate and grow until a critical susceptibility is reached, in which magnetic attraction overcomes dispersive forces, leading to agglomeration and precipitation. This phase change in the system arrests nanoparticle growth and gives true thermodynamic control over the size of nanoparticles. We then show that increasing the alkyl chain length of the surfactant, and hence increasing steric stabilization, allows nanoparticles to grow to larger sizes before agglomeration occurs. Therefore, simply by choosing the correct surfactant, the size and magnetic properties of iron nanoparticles can be tailored for a particular application. With the continuous addition of the precursor solution, we can repeat the steps of nucleation, growth, and magnetic agglomeration indefinitely, making the approach suitable for large scale syntheses.     

Influence of Potassium Metal-Support Interactions on Dendrite Growth

Combined synchrotron X-ray nanotomography imaging, cryogenic electron microscopy (cryo-EM) and modeling elucidate how potassium (K) metal-support energetics influence electrodeposit microstructure. Three model supports are employed: O-functionalized carbon cloth (potassiophilic, fully-wetted), non-functionalized cloth and Cu foil (potassiophobic, nonwetted). Nanotomography and focused ion beam (cryo-FIB) cross-sections yield complementary three-dimensional (3D) maps of cycled electrodeposits. Electrodeposit on potassiophobic support is a triphasic sponge, with fibrous dendrites covered by solid electrolyte interphase (SEI) and interspersed with nanopores (sub-10 nm to 100 nm scale). Lage cracks and voids are also a key feature. On potassiophilic support, the deposit is dense and pore-free, with uniform surface and SEI morphology. Mesoscale modeling captures the critical role of substrate-metal interaction on K metal film nucleation and growth, as well as the associated stress state.     

Oxidation of enones to α′-acetoxyenones using manganese triacetate

The oxidation of α,β-unsaturated ketones with manganese (III) triacetate in benzene furnishes α'-acetoxyenones in good yields.     

Binding studies of nNOS-active amphibian peptides and Ca2+ calmodulin, using negative ion electrospray ionisation mass spectrometry

Amphibian peptides which inhibit the formation of nitric oxide by neuronal nitric oxide synthase (nNOS) do so by binding to the protein cofactor, Ca2+calmodulin (Ca2+CaM). Complex formation between active peptides and Ca2+CaM has been demonstrated by negative ion electrospray ionisation mass spectrometry using an aqueous ammonium acetate buffer system. In all cases studied, the assemblies are formed with a 1:1:4 calmodulin/peptide/Ca2+ stoichiometry. In contrast, the complex involving the 20-residue binding domain of the plasma Ca2+ pump C20W (LRRGQILWFRGLNRIQTQIK-OH) with CaM has been shown by previous two-dimensional nuclear magnetic resonance (2D NMR) studies to involve complexation of the C-terminal end of CaM. Under identical conditions to those used for the amphibian peptide study, the ESI complex between C20W and CaM shows specific 1:1:2 stoichiometry. Since complex formation with the studied amphibian peptides requires Ca2+CaM to contain its full complement of four Ca2+ ions, this indicates that the amphibian peptides require both ends of the CaM to effect complex formation. Charge-state analysis and an H/D exchange experiment (with caerin 1.8) suggest that complexation involves Ca2+CaM undergoing a conformational change to a more compact structure.     

Multimetal Fischer carbene complexes of Group VI transition metals: synthesis, structure and substituent effect investigation

Fischer carbene complexes of tungsten with substituents containing up to two additional different transition metals, with all the metals in electronic contact with the carbene carbon atom, were synthesised and studied both in solution and in the solid state. For the complexes of the type [W(CO)(5){C(OR')R}], the substituents chosen were heteroaromatic 2-benzo[b]thienyl (2-BT), or 2-BT π-bonded to a chromium tricarbonyl fragment ([Cr(CO)(3)(2-η(6)-BT)]) or ferrocenyl (Fc) as the R-substituent, while the OR'-substituent was systematically varied between an ethoxy or a titanoxy group, to yield the complexes 1b (R' = Et, R = 2-BT), 2b (R' = Et, R = [Cr(CO)(3)(2-η(6)-BT)]), 3b (R' = TiCp(2)Cl, R = 21-BT), 4b (R' = TiCp(2)Cl, R = [Cr(CO)(3)(2-η(6)-BT)]), 5b (R' = Et, R = Fc) and 6b (R' = TiCp(2)Cl, R = Fc). The structural features and their relevance to bonding in the multimetal carbene compounds of both these tungsten and the analogous chromium complexes were investigated as they represent indicators of possible reactivity sites in multimetal carbene assemblies. The possibility of using DFT calculations to quantify the effect of metal-containing substituents on the carbene ligands was tested and correlated with experimental parameters by employing methods such as vibrational spectroscopy, molecular orbital analysis, and cyclic voltammetry.