Character Of Na Research Articles

Orthographic Processing of Developmental Dyslexic Children in China: Evidence from an Event-Related Potential Study.

This study aimed to explore the orthographic processing of simplified Chinese characters in developmental dyslexic children in Kashgar, Xinjiang, China, and provide a theoretical basis for intervention strategies for developmental dyslexia in Chinese. Using event-related potential (ERP) measures, 18 developmental dyslexic children and 23 typically developing children performed a character decision task with three types of stimuli: real characters (RCs), pseudocharacters (PCs), and noncharacters (NCs). Behavioral results showed that the control children displayed a faster and higher accurate performance than the dyslexic children across PCs and NCs. ERP data revealed that the RCs and PCs elicited a stronger P200 than the NCs. Compared with the RCs and NCs, children in the control group showed more N400 negatives for PCs. It is worth mentioning that dyslexic children did not show any difference on N400, which reflected the insufficient orthographic processing of dyslexic children in China. These results show that Chinese dyslexic children had orthographic processing defects.

Impaired Orthographic Processing in Chinese Dyslexic Children: Evidence From the Lexicality Effect on N400

ABSTRACTThis study used the lexicality effects on N400 to investigate orthographic processing in children with developmental dyslexia. Participants performed a Go/No-Go semantic judgment task; three types of stimuli—real characters (RC), pseudocharacters (PC), and noncharacters (NC)—were embedded in No-Go trials. Two types of lexicality effects (RC vs. NC and PC vs. NC) were used to reflect the sensitivity to Chinese orthographic knowledge. In typical developing children, NC elicited a more negative N400 in frontal sites and a less negative N400 in bilateral posterior sites than RC and PC. The reversed lexicality effects in anterior and posterior sites support the dual-mechanism for lexical retrieval. Children with dyslexia revealed a more negative N400 for NC in frontal sites compared with RC, suggesting that they remained sensitive to orthographic familiarity. However, no difference between NC and PC was observed, suggesting a weakness in capturing Chinese orthographic knowledge in children with dyslexia.

The Acquisition of Orthographic Knowledge: Evidence from the Lexicality Effects on N400.

This study aimed to understand how reading ability shapes the lexicality effects on N400. Fifty-three typical developing children from the second to the sixth grades were asked to perform the pronounceability judgment task on a set of Chinese real characters (RC), pseudocharacters (PC) and non-characters (NC), as ERPs were recorded. The cluster-based permutation analysis revealed that children with low- to medium-reading ability showed greater negativity to NCs than to RCs and PCs in frontal sites from 300 to 450 ms, while children with high ability group showed a greater positivity to NCs than both RCs and PCs at central to posterior sites. Furthermore, the linear mixed model (LMM) analysis was applied to investigate the relationship between lexicality effects on N400 and reading-related behavioral assessments on a set of standardized tests (including character recognition, vocabulary size, phonological awareness, and working memory). The results found that in children with lower reading ability, the N400 elicited by NCs becomes more negative in the frontal sites. For children with higher reading ability, the N400 elicited by NCs became more positive than that elicited by RCs or PCs in the posterior sites. These findings demonstrate the developmental changes in the lexicality effects on N400 as children become more advanced readers and suggested that the lexicality effects on N400 can serve as neural markers for the evaluation of orthographic proficiency in reading development.

Electrochemistry Characteristics of NaNi0.5Mn1.5O4 As the Cathode Material for Sodium Ion Batteries

Introduction Lithium ion batteries have been widely used in portable electronic devices and deploying in electric vehicles and power grid energy storing. After the topic of the limited lithium source was mentioned, sodium ion batteries resurged in recent years. Many kinds of cathode materials for sodium ion batteries have been studied, but more research is needed to realize the commercial use of sodium ion batteries, especially competing with current lithium ion batteries. Because of large ion size, Na+ cannot stay in tetragon position in close-packed oxygen structure, so spinel structure of sodium oxide isn’t thermal stable phase, which can only synthesized at high pressure[1]. Naoaki Yabuuchi et al. [2] reported that product of electrochemical exchanged LiMn2O4 isn’t NaxMn2O4, but NaMnO2. The NaMnO2 prepared by electrochemical exchange show a very high capacity of 190 mAh/g and better capacity retention in the 2.3-4.3V range than the directly prepared NaMnO2. Here we report the structure change and electrochemical performance of NaNi0.5Mn1.5O4 prepared by electrochemical exchange method. Experimental Spinel LiNi0.5Mn1.5O4 was prepared by solid state method. Stoichiometry Li2CO3, Ni(OH)2 and Mn2O3 were ball-milled and then sintered at 800℃ for 24h in air. The obtained LiNi0.5Mn1.5O4 was chartered by XRD, SEM and charge-discharge testing. For preparation of NaNi0.5Mn1.5O4 via electrochemical exchange, LiNi0.5Mn1.5O4 was first charged to 4.9V in a cell with Li electrolyte and Li anode to de-insert all of the lithium ions. Then the cell was disassembled and the cathode electrode was took out and washed by DMC for three time followed by assembling it with Na electrolyte (NaClO4 in PC+FEC) and Na anode. Charge and discharge the sodium ion cell at 10 mA/g current between 2 and 4.5V. Results and discussion LiNi0.5Mn1.5O4 shows a long charge plateau at 4.7V in lithium cell, which represents de-intercalation of Li+ and oxidation of Ni2+. At the end of charge process, Ni0.5Mn1.5O4 with very few lithium ions was gotten whose character of Na+ intercalation and de-intercalation was investigated in following cycles in sodium cell. It could be found that a discharge plateau at about 3.6V corresponding about a capacity of 80 mAh/g (Fig.1a). The electrochemical behavior is similar as the NaMn2O4 whose initial discharge plateau locates at about 3.2V with a capacity of 80 mAh/g in sodium cell [2]. However, in NaNi0.5Mn1.5O4 system, the capacity between 2 and 3V is little, so the total capacity is only about 110mAh/g for the first discharge process and decrease quickly during the following cycles. The structure of cycled NaNi0.5Mn1.5O4 was investigated by XRD, shown in Fig.1b. The spinel structure is kept when lithium ion is replaced by sodium ion, though some should peaks appears, which caused by strain because of a size gap between Li+ and Na+. After cycling, though no peaks corresponding to layered NaMnO2 can be found, the capacity decreases obviously, so new capacity decrease mechanism should be considered. Reference [1] Xizheng Liu, Xi Wang, Akira Iyo, et al., J. Mater. Chem. A, 2014, 2, 14822-14826 [2] Naoaki Yabuuchi, Masaya Yano, Satoru Kuze, et al., Electrochim. Acta, 2012,82, 296–301 Figure 1

The Role of Acid Residues in Na+ Uptake and Binding in Na+-NQR from Vibrio Cholerae

The Na+-translocating NADH:quinone oxidoreductase (Na+-NQR) is the gateway for electrons into the respiratory chain of Vibrio cholerae and many other pathogenic bacteria. Na+-NQR is unique among respiratory enzymes in that it pumps sodium rather than protons.The character of Na+ binding to the enzyme is crucial to understanding the coupling between Na+ translocation and the redox reaction. We are using functional studies_steady state and transient kinetics and equilibrium binding_in combination with site-directed mutagenesis to investigate the interaction of Na+ with Na+-NQR. Recently, we have focused on conserved acid residues in membrane spanning regions as candidates for Na+ binding site ligands. Here, we describe results on two of these residues, which are both involved in Na+ uptake by the enzyme: NqrB-D397 and NqrE-E95.Replacement of either residue by a neutral amino acid (Ala) results in a large increase in the apparent Km for Na+. In the case of NqrB-D397, replacement by Glu or Cys, produced smaller changes in Kmapp, indicating that the size and charge of the residue at this position both modulate Na+ binding. Stopped-flow kinetic measurements show that mutations at both positions exert their effect specifically at one internal electron transfer step: 2Fe-2S center aFMNC. These results are consistent with the earlier finding that this is the first Na+ dependent electron transfer step in the enzyme reaction. The results are discussed will be discussed in the context of our current model of Na+-NQR as a redox driven Na+ pump, that operates on the basis of kinetic rather than thermodynamic coupling.