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Yuan Deng

Publications and source records attributed to Yuan Deng.

8 recordsLinked to original sources
PubMed2007

Three-phase interlines electrochemically driven into insulator compounds: a penetration model and its verification by electroreduction of solid AgCl.

A dynamic three-phase interline model has been developed for the reduction of a solid insulating metal compound to the metal in a suitable electrolyte, focusing on the electrochemically driven penetration of the process (or the three-phase interlines) into the insulator. Consideration is given to the effects of electrochemical, concentration and ohmic polarizations in the reduction-generated porous metal layer on top of the solid compound. Under potentiostatic conditions, reduction in the depth direction (penetration) becomes progressively slower as a result of the rising ohmic and concentration polarizations, whilst the electrochemical polarization exerts a declining effect. The quantitative equations established here also provide simple methods for the determination of some kinetic parameters of the reduction process, including rho (total resistivity) and D(R) (diffusion coefficient). The model has been experimentally verified by electrochemical reduction of solid AgCl with two novel metal|AgCl cylinder electrodes in aqueous solutions.

Journal Article↗
PubMed2006

Electrochemically driven three-phase interlines into insulator compounds: electroreduction of solid SiO2 in molten CaCl2.

The electrochemical reduction of solid SiO2 (quartz) to Si is studied in molten CaCl2 at 1173 K. Experimental observations are compared and agree well with a novel penetration model in relation with electrochemistry at the dynamic conductor|insulator|electrolyte three-phase interlines. The findings show that the reduction of a cylindrical quartz pellet at certain potentials is mainly determined by the diffusion of the O(2-) ions and also the ohmic polarisation in the reduction-generated porous silicon layer. The reduction rate increases with the overpotential to a maximum after which the process is retarded, most likely due to precipitation of CaO in the reaction region (cathodic passivation). Data are reported on the reduction rate, current efficiency and energy consumption during the electroreduction of quartz under potentiostatic conditions. These theoretical and experimental findings form the basis for an in-depth discussion on the optimisation of the electroreduction method for the production of silicon.

Journal Article↗
PubMed2006

Specialization of phonological and semantic processing in Chinese word reading.

The purpose of this study was to examine the neurocognitive network for processing visual word forms in native Chinese speakers using functional magnetic resonance imaging (fMRI). In order to compare the processing of phonological and semantic representations, we developed parallel rhyming and meaning association judgment tasks that required explicit access and manipulation of these representations. Subjects showed activation in left inferior/middle frontal gyri, bilateral medial frontal gyri, bilateral middle occipital/fusiform gyri, and bilateral cerebella for both the rhyming and meaning tasks. A direct comparison of the tasks revealed that the rhyming task showed more activation in the posterior dorsal region of the inferior/middle frontal gyrus (BA 9/44) and in the inferior parietal lobule (BA 40). The meaning task showed more activation in the anterior ventral region of the inferior/middle frontal gyrus (BA 47) and in the superior/middle temporal gyrus (BA 22,21). These findings are consistent with previous studies in English that suggest specialization of inferior frontal regions for the access and manipulation of phonological vs. semantic representations, but also suggest that this specialization extends to the middle frontal gyrus for Chinese. These findings are also consistent with the suggestion that the left middle temporal gyrus is involved in representing semantic information and the left inferior parietal lobule is involved in mapping between orthographic and phonological representations.

Acoustic Stimulation↗
PubMed2006

[Clinicopathologic features of cardiac myxoma--a report of 47 cases].

BACKGROUND & OBJECTIVE: Myxoma is the most common neoplasm of the heart, and has various morphologic structures, but its biological behaviors and histogenesis are still controversial. This study was to summarize the clinical, histomorphologic, and immunophenotypic features of cardiac myxoma. METHODS: The clinical data and HE sections of 47 cases of cardiac myxoma were reviewed. Special staining and immunohistochemical staining for 10 kinds of antibodies were carried on some cases to observe the morphologic features. RESULTS: Of the 47 patients with cardiac myxoma, 32 were women, the youngest was 3 years old. The volume of tumors ranged from 0.7 cm x 0.7 cm x 0.4 cm to 12 cm x 8 cm x 7 cm. Of the 47 tumors, 42 were pedunculated, the rest had broad fundus without pedicel; 43 located in the left atrium, 3 in the right atrium, and 1 in the left ventricle where near to the apex of heart. Tumor cells were stellate, spindle, round, or irregular, and arranged as masses or stripes, with abundant mucus around them. Tumor cells surrounded arterioles in 4 cases. Pseudo-capsule was formed by hyperplastic fibrous tissue in 4 cases. The mesenchyma presented angiomatous fashion in 2 cases. Sheets of old hemorrhage, hemosiderin and iron salt deposition, and fibrosis were observed in 7 cases. One case had foci adenoid structure, 1 lipoid metaplasia and ossification, 1 was rich of cells. Vimentin and CD34 were found in lining cells and parenchymal cells in 12 cases. Cytokine kinase (CK) and epithelial membrane antigen (EMA) were positive in the region of adenoid differentiation. Proliferating cell nuclear antigen (PCNA) and Ki67 were positive in the cell-rich tumor. None of the 21 patients had tumor recurred after follow-up. CONCLUSIONS: Cardiac myxoma has various secondary morphologic changes, including adenoid metaplasia, old hemorrhage, fibrosis, ossification, and lipoid metaplasia. Whether the cell-rich tumors tend to be malignant needs further study. Cardiac myxoma may come from multipotential mesenchymal cells.

Adolescent↗
PubMed2005

Electrochemistry at conductor/insulator/electrolyte three-phase interlines: A thin layer model.

A thin layer model is proposed to assist in the understanding of the electrochemical conversion of insulator to conductor at the conductor/insulator/electrolyte three-phase interline (3PI) when the influence of mass diffusion in the electrolyte phase is negligible. The model predicts, under potentiostatic conditions, a linear variation of the current or the length of the 3PI with time. When polarization is sufficiently large, the logarithm of the current/time ratio or the 3PI-length/time ratio, according to the model, increases linearly with the applied potential. These predictions were tested against and agreed very well with two practical systems: the electroreduction of solid AgCl to Ag in aqueous KCl and of solid SiO2 to Si in molten CaCl2. Kinetic parameters were derived from experimental data using the model. Particularly, the electron transfer coefficient, alpha, was found to be about 0.29 for the reduction of AgCl to Ag in the aqueous KCl solution at room temperature but about 10(-2) for the reduction of SiO2 to Si in molten CaCl2 at 850 degrees C.

Journal Article↗
PubMed2004

fMRI evidence for the automatic phonological activation of briefly presented words.

Functional magnetic resonance imaging was used to investigate whether people generate the phonology of briefly presented words that they do not attend. This was done in Chinese by examining the effect of orthography-phonology regularity (i.e., how predictable the phonology of a word is from its components rather than whole-word form) with high- and low-frequency words, and by using a task that diverted participants' attention to a mask, rather than the words. The results showed that there was a significant interaction between regularity and word frequency in blood oxygen level-dependent (BOLD) signal, which mirrored the pattern found in behavioral data. Specifically, for low-frequency characters, bilateral fusiform gyri, the posterior superior temporal gyrus, and inferior parietal regions were more active when using irregular compared to regular characters. There were no significant differences when high-frequency characters were used. These results support the possibility that at least for low-frequency words, phonology is automatically generated when reading, even when people do not attend to the words and even in a language where the orthography-phonology mapping is extremely irregular.

Adolescent↗
PubMed2002

Giant dielectric permittivity observed in Li and Ti doped NiO.

A giant low-frequency dielectric constant ( epsilon 0 approximately 10(5)) near room temperature was observed in Li,Ti co-doped NiO ceramics. Unlike currently best-known high epsilon 0 ferroelectric-related materials, the doped oxide is a nonperovskite, lead-free, and nonferroelectric material. It is suggested that the giant dielectric constant response of the doped NiO could be enhanced by a grain boundary-layer mechanism as found in boundary-layer capacitors. In addition, there is about a one-hundred-fold drop in the dielectric constant at low temperature. This anomaly is attributed to a thermally excited relaxation process rather than a thermally driven phase transition, as for that yielding ferroelectrics.

Journal Article↗