Synthesis, Characterization, and Thermal Kinetics of Mixed Gadolinium: Calcium Heptamolybdate System.

Synthesis of mixed gadolinium calcium heptamolybdate (GdCaHM) system in silica gel medium using single gel single tube technique has been successfully achieved. The grown crystal exhibits various morphologies, which includes spherulites, multifaceted, and square platelets. The nature of the grown material was established by X-ray diffraction (XRD) studies. Fourier transform infrared spectroscopy (FTIR) study signifies the presence of heptamolybdate (Mo7O24) and water symmetry structure, whereas energy dispersive X-ray analysis (EDAX) establishes the stoichiometric of the grown crystal as GdCaMo7O24·8H2O. The thermal behaviour was studied using the thermoanalytical techniques, which include thermogravimetry (TG), differential thermal analysis (DTA), and differential scanning calorimetry (DSC). Results obtained on the application of TG based models, namely, Horowitz-Metzger, Coats-Redfern, and Piloyan-Novikova, suggest the contracting cylindrical model as the relevant model for the thermal decomposition of the material. The kinetic parameters, namely, the order of reaction (n), activation energy (E a ), frequency factor (Z), and entropy (ΔS∗), were also calculated using these three models.

Comparison of graphic symbol learning in individuals with aphasia and right hemisphere brain damage.

This study compared the differences in performance on recognition of graphic symbols across time by individuals with aphasia, individuals with right-hemisphere brain damage, and neurologically normal adults. The subjects, seen individually, learned 40 Blissymbols. The symbols were selected so that the effects of symbol translucency and complexity on the recognition of graphic symbols could be examined. A paired-associate learning paradigm was used to teach the symbol-referent pairs to subjects. The results indicated that individuals with aphasia and neurologically normal adults do not differ significantly in recognition of graphic symbols. However, individuals with right-hemisphere damage recognized fewer symbols compared to individuals with aphasia and normal adults, suggesting that they have difficulty in associative learning of graphic symbols. Additionally, translucency was found to be a potent factor in the recognition of Blissymbols by all groups. The finding that individuals with severe chronic aphasia can learn and retain graphic symbols has significant clinical implications for aphasia rehabilitation.

Segmental intelligibility and speech interference thresholds of high-quality synthetic speech in presence of noise.

Technological advancement in the area of synthetic speech has made it increasingly difficult to distinguish quality of speech based solely on intelligibility scores obtained in benign laboratory conditions. Intelligibility scores obtained for natural speech and a high-quality text-to-speech system (DECtalk) are not substantially different. This study examined the perceived intelligibility and speech interference thresholds of DECtalk male and female voices and compared them with data obtained for natural speech. Results revealed that decreasing signal-to-noise levels had more deleterious effects on the perception of DECtalk male and female voices than on the perception of natural speech. Analysis of pattern of phoneme errors revealed that similar general patterns of errors tended to occur in DECtalk and in natural speech. The speech interference test did not demonstrate any significant difference between the DECtalk male and female voices. These results were supported by the absence of a significant difference between DECtalk male and female voices during intelligibility testing at different signal-to-noise ratios.