Mild solutions of non‐Lipschitz stochastic integrodifferential evolution equations

In this work, we study the existence and uniqueness of mild solutions for stochastic partial integrodifferential equations under local non‐Lipschitz conditions on the coefficients. Our analysis makes use of the theory of resolvent operators as developed by R. Grimmer as well as a stopping time technique. Our results complement and improve several earlier related works. An example is provided to illustrate the theoretical results. Copyright © 2016 John Wiley & Sons, Ltd.     

Sensitivity to local dipole fields in the CRAZED experiment: an approach to bright spot MRI

Local dipole fields such as those created by small iron-oxide particles are used to produce regions of low intensity (dark contrast) in many molecular magnetic resonance imaging applications. We have investigated, with computer simulations and experiments at 17.6 T, how the COSY revamped with asymmetric z-gradient echo detection (CRAZED) experiment that selects intermolecular double-quantum coherences can also be used to visualize such local dipole fields. Application of the coherence-selection gradient pulses parallel to the main magnetic field produced similar, dark contrast as conventional gradient echo imaging. Application of the gradient along the magic angle leads to total loss of signal intensity in homogeneous samples. In the presence of local dipole fields, the contrast was inverted and bright signals from the dipoles were observed over a very low background. Both simulations and experiments showed that the signal strongly decreased when a phase-cycle suppressing single-quantum coherences was employed. Therefore, we conclude that most of the signal comes from directly refocused magnetization or intermolecular single-quantum coherences. Finally, we demonstrate that bright contrast from local dipole fields can also be obtained, when the pair of coherence-selection gradient pulses is deliberately mismatched. Both methods allowed visualization of local dipole fields in phantoms in experimental times of about 3 min.     

Structural evolution and epitaxial stabilisation of pulsed laser deposited Sm0.55Nd0.45NiO3 solid solution nanostructured films on undoped Si (1 0 0) and NdGaO3 substrates

We report on the effects of substrate, ambient oxygen pressure and deposition time on the crystal structure, and morphology of Sm_0.55Nd_0.45NiO₃ solid solution nanostructured films synthesized by pulsed-laser deposition. In each film the structure was found to be consistent with a perovskite structure with preferential planes growth and reveals a strong orientation along the orthorhombic (2 1 0) plane of the perovskite subcell for the film deposited on NdGaO₃ where highly crystalline films were obtained within 15 min deposition time with a low surface roughness of 8.79 nm. Similar structure is observed on Si (1 0 0) substrate only at O₂ pressure of 0.4 mbar. The surface morphology of the different samples shows a net dense film structure with several droplets population. The nano-scaled droplets are in general spherical in shape; a detailed analysis indicates that the laser ablation of this nickelate family is governed to a certain extent by a heat transfer phenomenon.     

Model-independent dynamic constraint to improve the optical reconstruction of regional kinetic parameters

Optical dye-dilution techniques can quantify kinetic parameters in a region of tissue, but currently rely on a two-step process-spatial reconstruction of the dye concentration, repeated at every time-point, and subsequent kinetic analysis of the time-dependent change in dye concentration. Inaccuracies, in this approach, are due mainly to the ill-posed nature of the spatial reconstruction problem, which propagates into kinetic analysis and result in errors in extracted dynamic parameters. We present a hybrid kinetic deconvolution optical reconstruction algorithm, effectively combining optical reconstruction and model-independent kinetic analysis into a single inverse problem that is better posed. Kinetic parameters of multiple tissue regions can be quantified simultaneously. As proof of principle, we provide numerical experiments in reflectance-based and fluorescence molecular tomography scenarios.     

Local order in light emitting porous silicon studied by XEOL and TEY

The local structure of porous silicon has been studied exciting its optical luminescence by X-rays (XEOL). The photoluminescence yield and the total electron yield (TEY), recorded simultaneously as a function of the X-ray energy at the Si K edge, give rise to the extended X-ray absorption fine structures (EXAFS). Analysis of EXAFS data confirms that the optical luminescence of porous Si originates from the nanocrystalline cores and shows that XEOL–EXAFS and TEY–EXAFS are sensitive to different Si local environment. It can be assumed that XEOL–EXAFS is related only to the light emitting sites while TEY–EXAFS is sampling both luminescent and non-luminescent Si sites.     

Crystallographic report: Crystal and molecular structure of tetramethylammoniumdiisothiocyanatotriphenyltin(IV), [NMe4SnPh3(NCS)2]

The structure of NMe₄SnPh₃(NCS)₂ is molecular, without any significant intermolecular contacts in the lattice. The trigonal plane around the tin atom is defined by three carbon atoms from the phenyl groups and the axial positions occupied by the NCS groups. Copyright © 2003 John Wiley & Sons, Ltd.