A model for the acceptor state in II–VI compounds

The binding energy and the spatial distribution of an acceptor in an ionic semiconductor are calculated on the Anderson model with three parameters. The result is applied to the case of Li⁺, Na⁺, Cu⁺ and Ag⁺ in II–VI semiconductors. The parameters are evaluated by the dielectric theory of a chemical bond. It is shown that Li⁺ in ZnO, CdS, and CdSe forms an acceptor state with a larger amplitude at nearest-neighbor anion sites than at an impurity site; while Cu⁺ and Ag⁺ in Zn and Cd compounds have the opposite properties. The Na⁺ ion forms an acceptor state more localized densely at the impurity site in Zn compounds and vice versa in Cd compounds.     

Carbon-13 NMR spectra of all-trans-N-retinylidene-n-butylamine as an analogue of the Schiff's base linkage-compound in visual pigment

Carbon-13 NMR spectra have been obtained for all-trans-N-retinylidene-n-butylamine as an analogue of the Schiff's base linkage compound in visual pigment. The chemical shift changes on going from all-trans-retinal₁ to all-trans-N-retinylidene-n-butylamine are observed. These changes indicate the collapse of the bond alternation in conjugated polyene carbons, whereas N-protonation in all-trans-N-retinylidene-n-butylamine does not affect the bond alternation.     

Magnetic resonance in a [{Cr(CN)<Subscript>6</Subscript>} {Mn(S)-<Emphasis Type="Italic">pn</Emphasis>H-(H<Subscript>2</Subscript>O)}] · H<Subscript>2</Subscript>O single-crystal molecular ferrimagnet

The variations in the magnetic resonance spectra accompanying the transition from the paramagnetic to ferrimagnetic state in [{Cr(CN)₆} {Mn(S)-pnH-(H₂O) }] · H₂O orthorhombic chiral molecular crystals were studied. The dependence of the EPR linewidth on temperature in the proximity of the transition point T_C = 38 K argues for the two-dimensional character of spin ordering. The spin resonance line was found to undergo exchange narrowing at T > T_C. The ferrimagnetic phase has an easy magnetization axis coinciding with the a crystallographic axis.     

Effect of temporal resolution on the estimation of left ventricular function by cardiac MR imaging

The aim of this study was to investigate the effect of temporal resolution on the estimation of left ventricular (LV) function by cardiac magnetic resonance (MR) imaging using a steady-state free precession (SSFP) sequence. Left ventricular function was assessed by cine MR imaging using a segmented SSFP sequence in 10 healthy volunteers. Views per segment (VPS) were set at 8 and 20, resulting in high and low true temporal resolution, respectively. Irrespective of VPS, images were reconstructed at 40 cardiac phases, providing high apparent temporal resolution. Data were analyzed using 40, 20 and 10 phases to simulate different apparent temporal resolutions. Increasing the cardiac phases used for analysis slightly decreased mean end-systolic volume (ESV) and slightly increased mean ejection fraction (EF). No substantial difference in estimates of end-diastolic volume (EDV) was found between VPSs of 8 and 20. Imaging with a VPS of 20 yielded a larger ESV and smaller EF than imaging with a VPS of 8 when 40 phases were used. In conclusion, low true temporal resolution causes overestimation of ESV and underestimation of EF. Improvement of apparent temporal resolution mildly reduces but does not eliminate the errors caused by low true temporal resolution.     

Optical and magnetooptical properties of FePt-SiO<Subscript>2</Subscript> magnetic nanocomposites

The magnetic, optical, and magnetooptical properties of granular (FePt)_1?x(SiO₂)_x nanocomposites in the disordered state and after heat treatment were studied. The magnetooptical response of samples in which the concentration of the metallic component approached the percolation threshold was observed to become considerably enhanced. Modeling transverse Kerr effect (TKE) spectra in a straightforward effective medium approximation provided a qualitative fit to the experimental data over a broad concentration range. The dependences of the Kerr effect on the SiO₂ concentration in the nanocomposite are not monotonic and exhibit a sharp break near the percolation threshold. An analysis of the field dependences of the TKE and magnetization curves revealed that structural changes associated with ordering in annealed FePt films occur only in nanocomposites with fairly large grains.     

Novel soft chemical method for optically transparent Ru(bpy)3-K4Nb6O17 thin film

A unique guest-guest ion exchange method was developed for preparing a thin film of a nano-layered K(4)Nb(6)O(17).3H(2)O that possesses both (1) optical transparency and (2) ion-exchangeability under ambient conditions without calcination at high temperature. An optically transparent Ru(bpy)(3)(2+)-K(4)Nb(6)O(17) hybrid thin film, a photoresponsive electrode, was successfully prepared by the guest-guest exchange method by use of the intercalation compound MV(2+)-K(4)Nb(6)O(17) as a precursor. The optically transparent Ru(bpy)(3)(2+)-K(4)Nb(6)O(17) hybrid thin films have been characterized by X-ray diffraction, SEM, AFM, IR, and UV spectroscopies, as well as elemental analysis. The electrochemical behavior of the ITO/Ru(bpy)(3)(2+)-K(4)Nb(6)O(17) hybrid thin film electrode was studied; it also exhibits swift photoresponse in the visible region.