Addition of filler to polylactic acid (PLA) may affect its crystallization behavior and mechanical properties. The effects of talc and hydroxyapatite (HA) on the thermal and mechanical properties of two types of PLA (one amorphous and one semicrystalline) have been investigated. The composites were prepared by melt blending followed by injection molding. The molecular weight, morphology, mechanical properties, and thermal properties have been characterized by gel permeation chromatography (GPC), scanning electron microscope (SEM), instron tensile tester, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and dynamic mechanical analysis (DMA). It was found that the melting blending led to homogeneous distribution of the inorganic filler within the PLA matrix but decreased the molecular weight of PLA. Regarding the filler, addition of talc increased the crystallinity of PLA, but HA decreased the crystallinity of PLA. The tensile strength of the composites depended on the crystallinity of PLA and the interfacial properties between PLA and the filler, but both talc and HA filler increased the toughness of PLA.

E896 has measured Lambda production in 11.6A GeV/c Au-Au collisions over virtually the whole rapidity phase space. The midrapidity p(t) distributions have been measured for the first time at this energy and appear to indicate that the Lambda hyperons have different freeze-out conditions than protons. A comparison with the relativistic quantum molecular dynamics model shows that while there is good shape agreement at high rapidity the model predicts significantly different slopes of the m(t) spectra at midrapidity. The data, where overlap occurs, are consistent with previously reported measurements.

This paper presents studies of the optical properties of MgxZn1−xO nanocrystals below and at the phase transition range where the solubility is limited. For the nanocrystals of Mg composition 0%–30%, the samples were found to consist of the wurtzite structure and exhibited band edge absorption as well as photoluminescence (PL) blueshift of ∼0.25 eV. The cold temperature PL of the ZnO nanocrystals exhibits the A-exciton and the bound exciton with values similar to that of the bulk ZnO reference sample. In addition, the PL of the ZnO nanocrystals was found to be dominated by an emission, referred to as the ε-PL, at ∼3.32 eV that is ∼56 meV below the A-exciton. The characteristics of the ε-PL agree well with model calculations of an emission that involves a transition of conduction-band electrons to acceptorlike states having an acceptor binding energy of ∼116 meV. The room temperature PL exhibited a strong exciton component, which is convoluted with the ε-PL. The PL line shapes of the MgxZn1−xO samples of Mg composition ranging from 3% up to 30% were found to exhibit the inherent alloy broadening, which masks the excitonic emissions. For samples at the Mg composition range of 40%–50%, the PL exhibited multiple emission peaks at a wide range of the UV spectrum starting from ∼3.22 eV, which is that of ZnO, up to 4 eV. Additionally, the x-ray diffraction of these samples was found to have diffractions corresponding to the wurtzite as well as to the cubic structures. The results for higher Mg composition imply that the nanoalloys have the onset of phase separation at Mg composition of ∼40%.

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