Oxidation resistance and high-temperature mechanical properties of porous Si2N2O/Si3N4 composite ceramics

Liting Wei,Yangfang Wu 한양대학교 세라믹연구소 2019 Journal of Ceramic Processing Research Vol.20 No.3

Si2N2O/Si3N4 composite ceramics were prepared by pressureless sintered a Si3N4 and SiO2 mixture with 2 mol% Sm2O3. Theoxidation behavior and high-temperature strength of Si2N2O/Si3N4 composite materials have been examined. The typicaloxidation isotherm of Si2N2O/Si3N4 ceramic is represented by an asymptotic law. The oxidation rate for Si2N2O/Si3N4 was lowas compared with those for Si3N4 ceramic. Thin protective oxide scales formed after long exposures to air at 1400 oC andsubstantial crystallization of the intergranular glass phase with formation of Sm10(SiO4)6N2 occurred during oxidation. Besides,Si2N2O/Si3N4 composites showed excellent high-temperature strength like Si3N4 ceramic and the residual strength ratio can beup to 80 % at 1100 oC which is much higher than Si2N2O single-phase ceramic. The degradation of strength at highertemperature results from the increase of interganular glass phase due to diffusion of molecular oxygen.

Exchange of the VP5 of Infectious Bursal Disease Virus in a Serotype I Strain with that of a Serotype II Strain Reduced the Viral Replication and Cytotoxicity

Liting Qin,Xiaole Qi,Honglei Gao,Yulong Gao,Zhigao Bu,Xiaomei Wang 한국미생물학회 2009 The journal of microbiology Vol.47 No.3

Infectious bursal disease virus (IBDV), belonging to Avibirnavirus genus in the Birnaviridae family, consists of two segments of double-strand RNA. There are two distinct serotypes of IBDV, the pathogenic serotype I and the non-pathogenic serotype II. Comparison of the deduced amino acid sequences of a panel of VP5 genes retrieved from GenBank revealed a high identity among strains within the serotype I or serotype II group but a low identity between strains across two serotypes. In this study, we rescued two mosaic viruses, rGtGxVP5 and rGt2382VP5 by exchanging the VP5 gene of a cell culture-adapted serotype I Gt strain with its counterpart of the very virulent IBDV Gx strain, or a non-pathogenic 23/82 strain of the serotype II. In comparison to the parental strain rGt virus, the rGtGxVP5 showed the similar viral replication, cytotoxicity and the ability of inducing apoptosis; however, the other mosaic virus rGt2382VP5 had a lower titer and a reduced cytotoxicity. Although exchange of VP5 within serotype I group did not alter the viral replication and cytotoxicity of Gt strain, exchange of VP5 in the serotype I with that of a serotype II reduced the viral replication and cytotoxicity on chicken embryo fibroblast (CEF) cells. Therefore, the VP5 of serotype II may be one of the factors responsible for the distinct pathogenic features of two serotypes.

Detection and Analysis of Near-Miss Software Clones used NiCad Clone Detector

Liting Yu(우려정),Eun Man Choi(최은만) 한국정보과학회 2019 한국정보과학회 학술발표논문집 Vol.2019 No.12

In Situ X-Ray Observation and Simulation of Ratcheting-Fatigue Interactions in Solder Joints

Liting Shi,Yunhui Mei,Gang Chen,Xu Chen 대한금속·재료학회 2017 ELECTRONIC MATERIALS LETTERS Vol.13 No.1

Reflow voids created by solder oxidation reduce thereliability of lap joints. In situ visualization of reflow voids inSn-3Ag-0.5Cu (SAC305) lap-shear solder joints undercyclic stressing was realized by X-ray computed tomography(CT), while the ratcheting deformation of the solder jointswas monitored by a non-contact displacement detectingsystem (NDDS). The results revealed that the shapeevolution of reflow voids in solder joints, as characterized bythe sphericity of the voids, can be divided into three stages:i.e., the initial stage with a sharp drop, a stable stage, and arapidly declining stage. A new evolution law for describingthe progress of sphericity was proposed, and was furtherintroduced into a viscoplastic constitutive model based onthe OW-AF nonlinear kinematic hardening rule. Thedamage-coupled OW-AF model yielded an accurateestimation of the whole-life ratcheting behavior of Sn-3Ag-0.5Cu (SAC305) lap-shear solder joints.

Selective catalytic reduction of NOx with NH3 over titanium modified FexMgyOz catalysts: Performance and characterization

Liting Xu,Shengli Niu,Dong Wang,Chunmei Lu,Qi Zhang,Kang Zhang,Jing Li 한국공업화학회 2018 Journal of Industrial and Engineering Chemistry Vol.63 No.-

A series of titanium modified FexMgyOz catalysts were prepared by coprecipitation method and impregnation-coprecipitation method with microwave assistant and their catalytic capability in selective catalytic reduction (SCR) was evaluated. Appropriate amount of either titanium or TiO2 could both improve the catalytic performance of FexMgyOz catalyst, especially above 350 °C. 7.5%Ti–FexMgyOz catalyst with wide temperature range of 225–400 °C could achieve the maximum NOx conversion of 100%, while FexMgyOz/TiO2(b) catalyst exhibited the best catalytic performance in the present of H2O and SO2. Characterization results exhibited that γ-Fe2O3 was the main active phase, TiO2 was mainly in the form of anatase TiO2 and both titanium and magnesium existed in amorphous phase. The crystalline grain could be refined with the addition of either titanium or TiO2, as well as the increase of BET surface area and pore volume. The acid sites, redox ability and the chemisorbed oxygen were the most important factors in SCR reaction. The introduction of titanium and TiO2 had the effect of increasing the strength of the acid sites, which could attribute to the improvement of catalytic performance over titanium modified FexMgyOz catalysts.

NH3-SCR performance and characterization over magnetic iron-magnesium mixed oxide catalysts

Liting Xu,Shengli Niu,Chunmei Lu,Dong Wang,Kang Zhang,Jing Li 한국화학공학회 2017 Korean Journal of Chemical Engineering Vol.34 No.5

A series of magnetic iron-magnesium mixed oxide catalysts (Fe1−xMgxOz) were synthesized via a novel coprecipitation method with microwave thermal treatment, and their activity in NH3-SCR was tested on a quartz fixedbed reactor. Physical and chemical properties of the catalysts were characterized by X-ray diffraction (XRD), N2- adsorption-desorption, scanning electron microscopy (SEM) and energy dispersive spectrometry (EDS). Fe0.8Mg0.2Oz with excellent N2 selectivity and resistance to SO2 and H2O was validated as the proper SCR catalyst, with the maximum NOx conversion of 99.1% fulfilled at 325 oC. Activity was strongly influenced by the γ-Fe2O3 crystalline phase, and magnesium existed in an amorphous phase and interacted with iron oxide intensively to form solid solution in favor of SCR. For Fe0.8Mg0.2Oz catalyst, optimum pore diameter distribution, appropriate surface area, pore volume and abundant lattice oxygen on the surface could be guaranteed, which is good for the diffusion process and enhances the activity.

Depletion of Inositol Polyphosphate 4-Phosphatase II Suppresses Callosal Axon Formation in the Developing Mice

Ji, Liting,Kim, Nam-Ho,Huh, Sung-Oh,Rhee, Hae Jin Korean Society for Molecular and Cellular Biology 2016 Molecules and cells Vol.39 No.6

The corpus callosum is a bundle of nerve fibers that connects the two cerebral hemispheres and is essential for coordinated transmission of information between them. Disruption of early stages of callosal development can cause agenesis of the corpus callosum (AgCC), including both complete and partial callosal absence, causing mild to severe cognitive impairment. Despite extensive studies, the etiology of AgCC remains to be clarified due to the complicated mechanism involved in generating AgCC. The biological function of PI3K signaling including phosphatidylinositol-3,4,5-trisphosphate is well established in diverse biochemical processes including axon and dendrite morphogenesis, but the function of the closely related phosphatidylinositol-3,4,-bisphosphate (PI(3,4)P2) signaling, particularly in the nervous system, is largely unknown. Here, we provide the first report on the role of inositol polyphosphate 4-phosphatase II (INPP4B), a PI(3,4)P2 metabolizing 4-phosphatase in the regulation of callosal axon formation. Depleting INPP4B by in utero electroporation suppressed medially directed callosal axon formation. Moreover, depletion of INPP4B significantly attenuated formation of Satb2-positive pyramidal neurons and axon polarization in cortical neurons during cortical development. Taken together, these data suggest that INPP4B plays a role in the regulating callosal axon formation by controlling axon polarization and the Satb2-positive pyramidal neuron population. Dysregulation of INPP4B during cortical development may be implicated in the generation of partial AgCC.

Mechanical, dielectric properties and thermal shock resistance of porous Si2N2O/Si3N4 composite ceramics

Wei Liting,Yu Yinhu,Jiao Jiao 한양대학교 세라믹연구소 2018 Journal of Ceramic Processing Research Vol.19 No.2

Porous Si2N2O/Si3N4 composite ceramics were fabricated by gas pressure sintering of Si3N4 and SiO2 with Sm2O3 as sinteringadditive under N2 atmosphere. Porosity and β-Si3N4 phase of the composites are increased with the increasing α-Si3N4 contentin starting materials. The composite ceramics show high flexural strength (223 ~ 288 MPa at room temperature) and goodthermal shock resistance and the critical thermal shock temperature (ΔTc) could be up to 1100 oC. The dielectric propertiesare mainly influenced by the sample porosity and phase composition. The as-prepared Si2N2O / Si3N4 composite ceramicspossess both low dielectric constant (ε = 4.8-5.2) and loss tangent (tanδ = 0.0014-0.0063), combined with excellent mechanicalperformance and thermal shock resistance, showing Si2N2O/Si3N4 composite ceramics could be promising high-temperaturewave transparent materials.

Design and Analysis of an Automatic Voltage Regulator Microcontroller-based Distributed Power Supply

Xiumin Wang,Liting Jiang,Liang Shan,Zhengquan Li,Rihui Xiong,Jianbing Xu 보안공학연구지원센터 2015 International Journal of Smart Home Vol.9 No.5

The design of an automatic voltage regulator (AVR) microcontroller-based distributed DC power supply is presented. The system includes a photovoltaic (PV) power generation, commercial hardware drive power system, and a battery booster circuit. A software control technology is used for storage battery charging and discharging. The PID control algorithm is used to control AVR microcontroller to achieve maximum power point tracking (MPPT) and to improve system stability. In addition to the traditional battery power, the system can make full use of solar system for energy sustainability. Experiment results show that the proposed system outperforms the traditional system with respect to the function of track, monitor and fine-tune for system steady state.

Identification and prevention of heterotopias in mouse neocortical neural cell migration incurred by surgical damages during utero electroporation procedures

Bolin Wang,Liting Ji,카우식 비샤이,Changyu Li,허성오 한국통합생물학회 2020 Animal cells and systems Vol.24 No.2

In utero electroporation (IUE) is a useful technique for gene delivery in embryonic mouse brain. IUE technique is used to investigate the mammalian brain development in vivo. However, according to recent studies, IUE methodology has some limitations like the formation of artificial ectopias and heterotopias at the micro-injection site. Thus far, the artificial heterotopias generated by physical trauma during IUE are rarely reported. Here, we reported the artificial heterotopias and ectopias generated from surgical damages of micropipette in detail, and moreover, we described the protocol to avoid these phenotypes. For the experimental purpose, we transferred empty plasmids (pCAGIG-GFP) with green fluorescent-labelled protein into the cortical cortex by IUE and then compared the structure of the cortex region between the injected and un-injected cerebral hemispheres. The coronary section showed that ectopias and heterotopias were appeared on imperfect-injected brains, and layer maker staining, which including Ctip2 and TBR1 and laminin, can differentiate the physical damage, revealing the neurons in artificial ectopic and heterotopic area were not properly arranged. Moreover, premature differentiation of neurons in ectopias and heterotopias were observed. To avoid heterotopias and ectopias, we carefully manipulated the method of IUE application. Thus, this study might be helpful for the in utero electroporator to distinguish the artificial ectopias and heterotopias that caused by the physical injury by microneedle and the ways to avoid those undesirable circumstances.