Miscibility studies on blends of polycarbonate with syndiotactic polymethyl methacrylate

Miscibility of bisphenol-A polycarbonate (PC) and syndiotactic polymethyle methacrylate (sPMMA) blends was investigated by differential scanning calorimetry (DSC) and small-angle light scattering. Cloud-point measurements indicated the existence of both a lower critical solution temperature and an upper critical solution temperature, forming an immiscibility loop. This immiscibility gap was observed for PC blends with sPMMA of various molecular weights ranging from 8,300 to 55,000. The DSC study on solvent-cast and coprecipitated PC/sPMMA blends from tetrahydrofuran solutions showed a single glass transition, shifting regularly with composition. The annealing of the 50/50 composition within the immiscibility loop exhibited dual glass transitions, but the system reverted to a single phase upon annealing above the loop. Phase dissolution took place during annealing above the loop, followed by thermoxidative branching (cross-linking) reaction. Dry pellets of PC and sPMMA were melt mixed above the loop in a Mini-Max mixer/molder; these molded blends exhibited a single phase. © 1993 John Wiley & Sons, Inc.     

Neutron diffuse scattering in Fe3O4 due to molecular polarons

The results of a precise re-examination of neutron diffuse scattering above the Verwey transition of Fe₃O₄ are reported. A model to describe the properties of valence fluctuations at the B-site Fe-ions are proposed, which assumes the existance of “molecular polarons”. The experimental results of anisotropic distribution of diffuse scattering seem to give an evidence for the feasibility of the proposed model.     

Curvature Vacuum Correlations in N-Dimensional Einstein Gravity

Under the flat Euclidean space–time background, the expressions for the leading terms of several two-point curvature vacuum correlation functions in N-dimensional Einstein gravity are calculated by using the perturbative expansion of the metric. It is shown that the contributions of the leading terms of such two-point curvature vacuum correlation functions are all vanishing.     

Effect of the superconducting transition on phonon energies and lifetimes in lead

We have performed a high-resolution inelastic neutron scattering study of certain transverse phonons in lead. We find that neither the energies nor the linewidths change appreciably with the onset of superconductivity. This finding contradicts a recent experimental report, but is in accord with theoretical expectations.     

Crystal structures and Mössbauer spectra of spin-crossover iron(III) complexes of quinquedentate ligands

Magnetic properties, Mössbauer spectra and crystal structures of spin-crossover iron(III) complexes with a quinquedentate ligand [FeLX]BPh₄ are reported. X and L denote a unidentate ligand and a quinquedentate ligand, respectively. [Fe(mbpN)(im)]BPh₄ shows spin-crossover behavior in an appropriate organic solvent, and [Fe(mbpN)(lut)]BPh₄, [Fe(bpN)(py)]BPh₄ and [Fe(salten)X]BPh₄ (X=4me-py or 2me-im) show spin-crossover behavior in a solid and in an organic solvent. It was found that the ligand field strength of salten was stronger than that of mbpN. The rates of spin-state interexchange in the complexes are as fast as the inverse of the lifetime (1×10^–7 s) of the Mössbauer nuclear level. The Mössbauer spectroscopic behavior of [Fe(mbpN)(lut)]BPh₄ and [Fe(bpN)(py)]BPh₄ is different to that of [Fe(salten)X]BPh₄ (X=4me-py or 2me-im). The difference was ascribed to the different geometrical positions of the corresponding anions.     

Calculation of Curvature Vacuum Correlations in R-Gravity

Under the flat Minkowski space-time background, using the perturbative expansion of the metric density, we calculate the expressions of the leading terms of several two-point curvature vacuum correlation functions in N-dimensional R-gravity, resulting in that the contributions of the leading terms of the curvature vacuum correlation functions are all vanishing.     

Site equivalent all Apex 1 nm-particle of CdSe preferentially grown in solution

A 1-nm particle of CdSe showing a sharp photoabsorption peak at 350 nm has been selectively synthesized as a single species in solution. Solid NMR spectra of both atoms show a single narrow peak of large chemical shift anisotropy and asymmetry compared with the essentially isotropic bulk CdSe. This result indicates that this extremely small 1-nm particle has most of its atoms at the surface, and the atoms are deformed from the sp³ configuration of the bulk fragment into an assembly consisting entirely of apexes of equivalent symmetry that are particularly stable and preferentially grown. This observed selective stability presents the possibility of growing 1-nm particles with an atomic monostructure in macroscopic quantities.     

Neutron spin-wave scattering from a Heusler alloy Pd2MnSn

Spin-wave dispersion relations have been determined in three principal symmetry directions for Heusler-type alloy Pd₂MnSn. Analysis shows that the exchange parameters at large distances have an oscillatory character which can be interpreted in terms of the s-d interaction model. However the n.n and n.n.n. interactions have the opposite sign to that expected from the model and should be attributed to other mechanisms.     

Antiproton distribution in antiproton-nucleus interaction and leading cluster cascade model

We investigate the leading antiproton productions in antiproton-nucleus collisions in terms of the leading cluster cascade model. It is pointed out that the energy degradation effect on \(\bar p\) A annihilation probability plays an important role to explain the \(\bar p\) spectra at small Feynman-x regions.