ABSTRACT
Objective To study the characteristics of the working memory in patients with Chinese aphasia in different ways of tasks and test materials .Methods Fifteen aphasia patients (aphasia group ,54~70 years old) and fifteen matched normal cases (control group) were requested to finish auditory retelling and auditory recognition tests of numerical materials ,content and function words .The maximum length of the string correctly completed was referred to as the working memory span .The working memory span was compared between the two groups .Results The working memory span of the aphasia group was significantly smaller than that of in the normal group (P<0 .01) .The working memory span of in patients with the aphasia group in the positive sequence retelling tasks were significantly greater than in reverse retelling ,positive recognition and reverse recognition (P<0 .01) .Reverse retell-ing was significantly greater than reverse recognition (P<0 .01) .The positive recognition was significantly greater than the reverse recognition(P<0 .01) .In retelling tasks ,the order of the working memory span was numbers , function words ,content words from high to low in the aphasia group ,but there was no significant difference be-tween them .In the positive recognition tasks ,the average working memory span for the numerical material was sig-nificantly greater than the content words(P< 0 .01) and the function words(P< 0 .01) .The content words were greater than the function words(P<0 .01) .In the reverse recognition tasks ,average working memory span for the numerical material was significantly greater than the function words (P<0 .01) .Conclusion The working memoryspan of in patients with aphasics significantly lags behind the normal people .Numbers are the easiest for aphasics . In different task modes ,the difficulties from high to low are as follow :positive retelling ,reverse retelling ,positive recognition and reverse recognition .
ABSTRACT
BACKGROUND: Inhibitory coating can prevent nanoparticle oxidation, grain growth, corrosion and agglomeration, and endow nanoparticle with special properties. ABJECTIVE: To prepare SiO2/Ni core-shell type nanoparticles and assess their magnetic properties. DESIGN, TIME AND SETTING: The observation experiment was performed between November 2005 and March 2006 at Nanometer Compound Material Research Laboratory of Dalian University of Technology, Dalian, Liaoning Province, China. MATERIALS: Nanometer nickel powder prepared by DC arc plasma jet method, Na2SiO3 produced by Bazhou Chemical Industry Branch Factory of Tianjin Quartz Clock Factory (China).METHODS: SiO2/Ni core-shell type nanoparticles were synthesized by coating a layer of SiO2 on the surface of manometer nickel powder via liquid deposition method using Na2SiO3 as the main source material. MAIN OUTCOME MEASURES: Their microstructures and material properties were investigated by X-ray diffraction, Fourier transform infrared spectrometer, transmission electron microscopy, thermo-gravimetric analysis, differential scanning calorimetry and vibrating sample magnetometer. RESULTS: The experimental results showed that SiO2 shell was in an amorphous state around Ni cores and it avoided agglomeration of the Ni nanoparticles. The oxidation temperature of nanometer nickel powder coated by SiO2 elevated from 287 ℃ to 385 ℃. The analysis result of magnetic properties indicated that the hysteresis loop of Ni had an excursion for the existence of anti-ferromagnetic NiO, the silica coating reduced the saturation magnetization and improved the coercivity. CONCLUSION: Preparation of SiO2/Ni core-shell type nanopartieles was successful; silica coating improved the oxidation resistance of nanometer nickel powder, endowed nanometer nickel powder better ferromagnetism and improved the coercivity.