Electrodeposition of Ag nanoparticles onto carbon coated TEM grids: A direct approach to study early stages of nucleation

An innovative experimental approach to study the electrodeposition of small nanoparticles and the early stages of electrochemical nucleation and growth is presented. Carbon coated gold TEM grids are used as substrates for the electrodeposition of silver nanoparticles so that electrochemical data, FESEM, HAADF–STEM and HRTEM data can be acquired from the same sample without the need to remove the particles from the substrate. It is shown that the real distribution of nanoparticles cannot be resolved by FESEM whereas HAADF–STEM analysis confirms that a distribution of ‘small’ nanoparticles (d ≈ 1–2 nm) coexist with ‘large’ nanoparticles corresponding to a bimodal size distribution. Besides, particles grown under the same conditions have been found to present different structures such as monocrystals, polycrystals or aggregates of smaller particles.     

New model for gas evolving electrodes based on supersaturation

A new model for gas evolving electrodes is proposed, in which the gas evolution reaction is driven by the supersaturation of dissolved gas.     

The electronic structure of bis(o-phenylenediamido)nickel,Ni[C6H4(NH)2]2

Extended Hückel and multiple scattering Xα calculations are reported for the title complex. Both sets of results are in quantitative agreement, suggesting that part of the unusual spectral and electrochemical properties of this system may be ascribed to the predominantly ligand character of the HOMO and LUMO orbitals.     

Integrating replication processes with mechanically interlocked molecular architectures

A kinetic model for the integration of self-replication with the formation of a mechanically interlocked molecular architecture, namely a rotaxane, is presented. The logical steps required to convert this model into molecular structures through consideration of the design criteria highlighted by the model are discussed and executed. Ultimately, despite careful design, the rotaxane synthesised did not replicate as expected. The reasons for this failure are traced by experiment and computation to the sub-optimal association constant for the pseudorotaxane complex required to form the replicating rotaxane. Additionally, a deleterious supramolecular steric effect, operating through the proximity of the macrocyclic component of the pseudorotaxane to the transition state for the stoppering reaction is identified computationally.     

The electronic structure of Cu(ethanediimine)+2

Extended-Hückel and multiple-scattering Xα molecular orbital calculations are reported for the Cu(ethanediimine)⁺₂ complex. The results obtained are in agreement. From the calculated electronic transition energies, it is inferred that the lowest excited state is a B₂ state of metal-to-ligand charge-transfer type, confirming resonance Raman results.     

Identification of bubble evolution mechanisms during AC electrograining

Bubble evolution during AC-graining is analysed in combination with the variation of the anodic peaks of the potential and the electrode surface morphology. Aluminium samples are grained in hydrochloric acid in an Inverted Rotating Disk Electrode. A roughness tester is used to characterise the electrode surface, while shadow imaging is applied to determine the bubble size distribution. An interpretation of the correlation existing among bubble size, potential peaks evolution, surface properties and smut layer formation is proposed, which provides insights into the mechanisms involved in bubble formation.     

Periodic inclusion of room-temperature-ferromagnetic metal phosphide nanoparticles in carbon nanotubes

We demonstrate the use of sequential catalytic growth to encapsulate iron, nickel-iron, and iron-cobalt phosphide catalyst nanoparticles periodically along the entire lengths of carbon nanotubes. Investigations by local electron spectroscopies and electron diffraction reveal the compositions and crystal structures of the encapsulated particles. Significantly, high spatial resolution magnetic characterization using magnetic force microscopy and off-axis electron holography demonstrates that encapsulated iron-cobalt phosphide nanoparticles are ferromagnetic at room temperature, in accordance with the properties of bulk metal phosphides of the same structure and composition.     

A method to investigate intervertebral disc morphology from MRI in early idiopathic scoliosis: a preliminary evaluation in a group of 14 patients

The aim of the study was to implement a methodology to quantify in vivo and from magnetic resonance imaging (MRI) the 3D geometrical properties of intervertebral discs (IVDs) in early idiopathic scoliosis with small curves. MRI data were posttreated using a custom-made image processing software to semiautomatically determine the location of disc centres, the location of the nucleus pulposus (NP) and the ratio between the NP volume and the disc volume. MRI was performed in a clinical protocol involving 14 patients having an early idiopathic scoliosis. First, the 3D reconstruction errors were quantified using a reproducibility test (intraoperator and interoperator) in one IVD (L5-S1). The maximal errors in location were 0.79 mm in the frontal plane, 1.84 mm in the sagittal plane and 0.76 mm in the vertical plane. The maximal error in relative volume was 42%. Second, the nucleus migration and relative volume were quantified in discs T5-T6 to L5-S1. No significant relative volume variation was detected. Concerning the disc migration, no significant differences were found in the sagittal and axial planes. In the frontal plane, significant differences were observed at the apex of the scoliotic curvature when the Cobb angle was > or =20 degrees . This innovative study in early scoliosis showed reproducible preliminary results, and its application to improve diagnosis and follow-up will be established in an enlarged patient database.