Effect of fabrication conditions on I-V properties for ZnO varistor with high concentration additives by sol-gel technique

Jincang Zhang,Shixun Cao,Ruiying Zhang,Liming Yu,Chao Jing 한국물리학회 2005 Current Applied Physics Vol.5 No.4

Polycrystalline nano-grain-boundary multi-doping ZnO-based nonlinear varistors with higher concentration additives have beenfabricated by solgel and standard solid-state reaction method, of which the best sample has a very high threshold voltage ofEb ¼ 3300 V/mm. The eect of sintering processes, sintering temperature and sintering time, and that of additive concentration ofBi2O3 on Eb of the samples are systematically investigated. The results show that the great merit of solgel method is its highthreshold voltage obtained by a lower sintering temperature than the solid-state reaction method. The present work also shows thatve phases including solid-state sintering, rich Bi liquid phase formation and ZnO as well as other additive dissolution, ZnO graingrowth, the secondary phase sucient formation and evolution have been experienced at dierent sintering temperatures. The holetype defect and nonhomogeneity of the microstructure will lead to the decrease of threshold voltage, i.e., the grain size and thehomogeneity of the material will be important factors and directly aect the characteristic of the varistor. The sintering charac-teristic and the inuence of Bi2O3 content on the threshold voltage are also discussed..

Cell-autonomous reduction of CYFIP2 is insufficient to induce Alzheimer’s disease-like pathologies in the hippocampal CA1 pyramidal neurons of aged mice

Ruiying Ma,Yinhua Zhang,Huiling Li,강혜림,김윤희,한기훈 한국통합생물학회 2023 Animal cells and systems Vol.27 No.1

Cytoplasmic FMR1-interacting protein 2 (CYFIP2) is an evolutionarily conserved multifunctionalprotein that regulates the neuronal actin cytoskeleton, mRNA translation and transport, andmitochondrial morphology and function. Supporting its critical roles in proper neuronaldevelopment and function, human genetic studies have repeatedly identified variants of theCYFIP2 gene in individuals diagnosed with neurodevelopmental disorders. Notably, a fewrecent studies have also suggested a mechanistic link between reduced CYFIP2 level andAlzheimer’s disease (AD). Specifically, in the hippocampus of 12-month-old Cyfip2heterozygous mice, several AD-like pathologies were identified, including increased levels ofTau phosphorylation and gliosis, and loss of dendritic spines in CA1 pyramidal neurons. However, detailed pathogenic mechanisms, such as cell types and their circuits where thepathologies originate, remain unknown for AD-like pathologies caused by CYFIP2 reduction. In this study, we aimed to address this issue by examining whether the cell-autonomousreduction of CYFIP2 in CA1 excitatory pyramidal neurons is sufficient to induce AD-likephenotypes in the hippocampus. We performed immunohistochemical, morphological, andbiochemical analyses in 12-month-old Cyfip2 conditional knock-out mice, which havepostnatally reduced CYFIP2 expression level in CA1, but not in CA3, excitatory pyramidalneurons of the hippocampus. Unexpectedly, we could not find any significant AD-likephenotype, suggesting that the CA1 excitatory neuron-specific reduction of CYFIP2 level isinsufficient to lead to AD-like pathologies in the hippocampus. Therefore, we propose thatCYFIP2 reduction in other neurons and/or their synaptic connections with CA1 pyramidalneurons may be critically involved in the hippocampal AD-like phenotypes of Cyfip2heterozygous mice.

Simple and green fabrication of a biomass-derived N and O self-doped hierarchical porous carbon via a self-activation route for supercapacitor application

Yang Binbin,Zhang Deyi,He Jingjing,Wang Yuling,Wang Kunjie,Li Hongxia,Wang Yi,Miao Lei,Ren Ruiye,Xie Mei 한국탄소학회 2020 Carbon Letters Vol.30 No.6

To meet the increased performance and cost requirements of commercial supercapacitor, a N and O self-doped hierarchical porous carbon is fabricated via a green and simple self-activation route utilizing leaves of wild hollyhock as raw materials. Comparing to commercial activated carbon, the reported material exhibits some marked merits, such as simple and green fabrication process, low cost, and superior capacitance performance. The specifc surface area of the obtained N and O co�doped hierarchical porous carbon arrives 954 m2 g−1, and the content of the self-doped nitrogen and oxygen reaches 2.64 at.% and 7.38 at.%, respectively. The specifc capacitance of the obtained material reaches 226 F g−1 while the specifc capacitance of the symmetric supercapacitor arrives 47.3 F g−1. Meanwhile, more than 90.3% of initial specifc capacitance is kept under a current density of 20 A g−1, and no arresting degradation is observed for capacitance after 5000 times cycle, perfectly demonstrating the excellent cycle and rate capability of the obtained material. The obtained N and O co-doped hierarchical porous carbon are expected to be an ideal substitution for commercial activated carbon.

Effect of Bi(Zn1/2Nb2/5)O3 addition on phase transition and energy storage properties of BaTiO3 ceramics

Ma Cuiying,Zhang Ruiying,Zhang Guangwei,Du Huiling,Liu Jia,Liang Ruinan,Wang Zhaoguo 한국물리학회 2023 Current Applied Physics Vol.55 No.-

Bi(Zn1/2Nb2/5)O3-modified BaTiO3 ceramics were designed with formula (1‒x)BaTiO3‒xBi(Zn1/2Nb2/5)O3 (0 ≤ x ≤ 0.15) and fabricated using conventional solid-state route. With increasing Bi(Zn1/2Nb2/5)O3 concentration, grain volume increased and phase structure was transformed from tetragonal to pseudo-cubic. Dielectric properties changed from temperature-dependent to temperature-insensitive and curves were flattened. Additionally, higher pseudo-cubic phase content induced slim P-E loop and low Pr. Therefore, 0.94BaTiO3‒0.06Bi(Zn1/2Nb2/5)O3 ceramic achieved energy storage density of 1.85 J/cm3 and high energy efficiency of 91.2% under electric field of 230 kV/cm. This energy storage density was 5 times higher than that of pure BT ceramic. Meanwhile, energy storage properties of this ceramic exhibited excellent thermal stability in the range of 30–120 °C and good frequency stability over 10–100 Hz. This work provides promising alternative option in energy storage materials.

Comparison of regression model and LSTM-RNN model in predicting deterioration of prestressed concrete box girder bridges

Gao Jing,Lin Ruiying,Zhang Yao 국제구조공학회 2024 Structural Engineering and Mechanics, An Int'l Jou Vol.91 No.1

Bridge deterioration shows the change of bridge condition during its operation, and predicting bridge deterioration is important for implementing predictive protection and planning future maintenance. However, in practical application, the raw inspection data of bridges are not continuous, which has a greater impact on the accuracy of the prediction results. Therefore, two kinds of bridge deterioration models are established in this paper: one is based on the traditional regression theory, combined with the distribution fitting theory to preprocess the data, which solves the problem of irregular distribution and incomplete quantity of raw data. Secondly, based on the theory of Long Short-Term Memory (LSTM) Recurrent Neural Network (RNN), the network is trained using the raw inspection data, which can realize the prediction of the future deterioration of bridges through the historical data. And the inspection data of 60 prestressed concrete box girder bridges in Xiamen, China are used as an example for validation and comparative analysis, and the results show that both deterioration models can predict the deterioration of prestressed concrete box girder bridges. The regression model shows that the bridge deteriorates gradually, while the LSTM-RNN model shows that the bridge keeps great condition during the first 5 years and degrades rapidly from 5 years to 15 years. Based on the current inspection database, the LSTM-RNN model performs better than the regression model because it has smaller prediction error. With the continuous improvement of the database, the results of this study can be extended to other bridge types or other degradation factors can be introduced to improve the accuracy and usefulness of the deterioration model.