Effect of annealing temperature on resistive switching behavior of Al/ La0.7Sr0.3MnO3 /LaNiO3 devices

Li Juanfei,Wu Lei,Ma Mingyu,Song Ruifeng,Dong Chunhui,Wei Junfang,Li Jinsheng,Wang Xiaoqiang,Li Mingya 한국물리학회 2023 Current Applied Physics Vol.46 No.-

La0.7Sr0.3MnO3 (LSMO)/LaNiO3 (LNO) thin films were deposited successively on Si single crystal by the sol-gel method. The bipolar resistive switching (RS) behavior was studied in Al/LSMO/LNO devices. Obvious current hysteresis was observed, the set (reset) voltage and resistance ratio were modulated by the annealing temperature of LSMO thin films. At the annealing temperature of 750 ◦C, good endurance and retention performance were obtained in the memory device. According to the fitting results of I–V curves, based on Schottky emission model, the conduction mechanisms of Al/LSMO/LNO devices were discussed. Our results may give a valuable insight on developing perovskite-type rare earth manganese oxide.

Variations of the stress intensity factors for a planar crack parallel to a bimaterial interface

Chunhui Xu,Taiyan Qin,Li Yuan,Nao-Aki Noda 국제구조공학회 2008 Structural Engineering and Mechanics, An Int'l Jou Vol.30 No.3

Stress intensity factors for a planar crack parallel to a bimaterial interface are considered. The formulation leads to a system of hypersingular integral equations whose unknowns are three modes of crack opening displacements. In the numerical analysis, the unknown displacement discontinuities are approximated by the products of the fundamental density functions and polynomials. The numerical results show that the present method yields smooth variations of stress intensity factors along the crack front accurately. The mixed mode stress intensity factors are indicated in tables and figures with varying the shape of crack, distance from the interface, and elastic constants. It is found that the maximum stress intensity factors normalized by root area are always insensitive to the crack aspect ratio. They are given in a form of formula useful for engineering applications.

Trimethyl-Ammonium Alkaline Anion Exchange Membranes with the Vinylbenzyl Chloride/Acrylonitrile Main Chain

Zhenghan Li,Junjie Chen,JinYue Zhou,YiWen Nie,Chunhui Shen,Shanjun Gao 한국고분자학회 2021 Macromolecular Research Vol.29 No.7

The main chain of polyolefin was synthesized by copolymerization of 4 - vinylbenzyl chloride (VBC) and acrylonitrile (AN), and trimethylamine is used for quaternization to prepare heterogeneous benzyl trimethyl-ammonium anion exchange membranes (Heter-X) and homogeneous benzyl trimethyl-ammonium anion exchange membrane (Homo-X). The results of Fourier-transform infrared (FT-IR), gel permeation chromatography (GPC), and 1H nuclear magnetic resonance (NMR) showed that VBC and AN were successfully copolymerized to form a polymer with a certain molecular weight, and trimethylamine was successfully quaternized. The prepared membranes exhibited good thermal stability and mechanical properties. The theoretical ion exchange capacity (IEC) values of Homo-3 and Heter-3 are the same, but the conductivity at 80 °C were 0.0572 S cm-1 and 0.0505 S cm-1. The results showed that the homogeneous method has a higher degree of quaternization and a more uniform distribution of quaternary ammonium groups, forming a more obvious microphase separation structure, which can also be seen in the atomic force microscopy (AFM) diagram. After being soaked in 1M KOH solution for 480 h, the ionic conductivity of Homo-6 and Heter-6 can still remain 91.4% and 85.5%, and the IEC loss rates were 17.21% and 24.34%. These results indicate that the prepared membranes are promising materials for application in fuel cells.

Numerical modeling and global performance analysis of a 15-MW Semisubmersible Floating Offshore Wind Turbine (FOWT)

Da Li,Ikjae Lee,Cong Yi,Wei Gao,Chunhui Song,Shenglei Fu,Moohyun Kim,Alex Ran,Tuanjie Liu Techno-Press 2023 Ocean systems engineering Vol.13 No.3

The global performance of a 15 MW floating offshore wind turbine, a newly designed semisubmersible floating foundation with multiple heave plates by CNOOC, is investigated with two independent turbine-floater-mooring coupled dynamic analysis programs CHARM3D-FAST and OrcaFlex. The semisubmersible platform hosts IEA 15 MW reference wind turbine modulated for VolturnUS-S and hybrid type (chain-wire-chain with clumps) 3×2 mooring lines targeting the water depth of 100 m. The numerical free-decay simulation results are compared with physical experiments with 1:64 scaled model in 3D wave basin, from which appropriate drag coefficients for heave plates were estimated. The tuned numerical simulation tools were then used for the feasibility and global performance analysis of the FOWT considering the 50-yr-storm condition and maximum operational condition. The effect of tower flexibility was investigated by comparing tower-base fore-aft bending moment and nacelle translational accelerations. It is found that the tower-base bending moment and nacelle accelerations can be appreciably increased due to the tower flexibility.

Variations of the stress intensity factors for a planar crack parallel to a bimaterial interface

Xu, Chunhui,Qin, Taiyan,Yuan, Li,Noda, Nao-Aki Techno-Press 2008 Structural Engineering and Mechanics, An Int'l Jou Vol.30 No.3

Stress intensity factors for a planar crack parallel to a bimaterial interface are considered. The formulation leads to a system of hypersingular integral equations whose unknowns are three modes of crack opening displacements. In the numerical analysis, the unknown displacement discontinuities are approximated by the products of the fundamental density functions and polynomials. The numerical results show that the present method yields smooth variations of stress intensity factors along the crack front accurately. The mixed mode stress intensity factors are indicated in tables and figures with varying the shape of crack, distance from the interface, and elastic constants. It is found that the maximum stress intensity factors normalized by root area are always insensitive to the crack aspect ratio. They are given in a form of formula useful for engineering applications.

A Multi-Mechanisms Composite Frequency Up-Conversion Energy Harvester

Ping Li,Nuo Xu,Chunhui Gao 한국정밀공학회 2020 International Journal of Precision Engineering and Vol.21 No.9

In this paper, a novel broadband hybrid piezoelectric-electromagnetic-electrostatic energy harvester with frequency up conversion is proposed to improve the harvesting bandwidth and energy conversion efficiency. The designed device generates vibration energy with much higher frequency than ambient vibration frequency, which uses the magnet to impact periodically on the piezoelectric cantilever with the top electrode of electrostatic element. The dynamic model of the hybrid energy harvester is established, and performances are experimental tested under the sinusoidal excitation and practical application environment. The results show that multi-mechanisms composite structure can realize the complementary advantages of electrostatic-piezoelectric-electromagnetic mechanisms and improve the energy conversion efficiency effectively compared with a single harvesting mechanism. The fabricated harvester can output electric energy in the frequency range of 1–38 Hz, which significantly reduces frequency dependence, and the maximum power is measured to be 11.7 mW and 12 mW during cycling and walking respectively, which is the sum of the power generated by three different elements. Furthermore, the fabricated prototype can also light up six light-emitting diodes (LEDs) simultaneously when handy shaking.

Overexpression of a Phosphatidylinositol-Specific Phospholipase C Gene from Populus simonii ×  P. nigra Improves Salt Tolerance in Transgenic Tobacco

Sun Yao,Li Yao,Sun Xin,Wu Qiong,Yang Chunhui,Wang Lei 한국식물학회 2022 Journal of Plant Biology Vol.65 No.5

Phosphatidylinositol-specific phospholipase C (PI-PLC) catalyzes the hydrolysis of phosphatidylinositol-4,5-bisphosphate into diacylglycerol and inositol 1,4,5-trisphosphate. It can play an essential role in plant stress response and signaling. However, the functions of PLCs remain unclear in wooden plants. This study carried out the bioinformatics analysis of the PLC gene family in poplar. The expression pattern analysis suggested the transient up-regulation of PsnPLC in salt stress conditions. The transgenic tobacco plants overexpressing PsnPLC were generated by the Agrobacterium-mediated leaf disc method. The transgenic lines showed a significant increase in plant height, SOD and POD activity, and proline content under salt stress. By contrast, transgenic lines showed a decreased malondialdehyde content under salt stress. Comparative transcriptome analysis indicated that the overexpression of PsnPLC mainly affects membrane-associated GO terms and signaling pathways, and the differential expression of salt-responsive genes may contribute to the enhanced salt tolerance. Overall, the results indicated that PsnPLC plays an essential role in modulating salt tolerance in transgenic tobacco.

Production of Tween 80-inducing Esterase by Acinetobacter sp. B1 Using Response Surface Methodology

Ma, Peiyu,Li, Yuqi,Miao, Chensi,Sun, Yunpeng,Liu, Chunhui,Li, Huijuan The Korean Society for Microbiology and Biotechnol 2019 한국미생물·생명공학회지 Vol.47 No.1

Esterase produced by Acinetobacter sp. B1 (strain B1) was optimized by means of one-variable-at-a-time and response surface methodologies. Results of the one-variable-at-a-time experiment showed that Tween 80 significantly increased esterase production of strain B1. The addition of Tween 80 to the culture medium increased the biomass and esterase activity of strain B1, stimulated content of total extracellular protein, and enhanced the oleic acid (C18:1) composition in the cell membrane of strain B1. The influence of eight culture variables on esterase production was evaluated by Plackett-Burman design. Results showed that Tween 80, pH, and $K_2HPO_4$ significantly affected the esterase production of strain B1. Tween 80, pH, and $K_2HPO_4$ were further optimized by central composite design. Under the optimized conditions (w/v, soluble starch 2.5%, tryptone 1.5%, Tween 80 0.8%, $K_2HPO_4$ 0.5%, NaCl 0.5%, pH 8.0, inoculum size 1%, and inoculum age 24 h), the maximum esterase activity of strain B1 was 152.13 U/ml, which was 10-fold higher than that of non-optimization after 36 h cultivation.

Effects of exposure to trace pyriproxyfen on the intestinal bacterial diversity and immune signal pathways of silkworm (Bombyx mori) larvae

Lu Qingyu,Li Guoli,Lan Huangli,Yu Dongliang,Yin Xingcan,Yang Wenqi,Yang Zehao,He Chunhui,Mo Danmei,Xu Kaizun 한국응용곤충학회 2022 Journal of Asia-Pacific Entomology Vol.25 No.2

Silkworm (Bombyx mori) is a widely used lepidopteran model insect. Pyriproxyfen is an insect growth regulator (IGR) that can be used to control pests such as lepidoptera and diptera, and there is no research about its in fluence on the intestinal bacterial diversity and immune signal pathway of non-target lepidopteran insect larvae. In this study, we treated fifth-instar silkworms with trace pyriproxyfen (10 − 4 mg/L). The results showed that the abundance and diversity of silkworm larvae intestinal flora at the level of phylum, class, order, family and genus were all changed. The function prediction result showed that the functional changes mainly focused on tran scription, amino acid transport and metabolism, carbohydrate transport and metabolism, signal transduction mechanisms, energy production and conversion et al. after exposure to trace pyriproxyfen. Furthermore, qRTPCR results showed that trace pyriproxyfen exposure activated the transcriptions of antimicrobial peptides (AMPs) genes regulated by Toll and IMD pathways. This research can lay the foundation for the study on the resistance of lepidopteran insects to pyriproxyfen and other juvenile hormone pesticides.

Review of research on safety control of seismic wave and shock wave induced by underwater blasting

Yaxiong Peng,Li Wu,Ying Su,Binbin Zhu,Chunhui Chen,Bo Li 한국자원공학회 2017 Geosystem engineering Vol.20 No.3

The safety control methods and indexes of seismic wave and shock wave induced by underwater blasting are, respectively, elaborated in this paper. The single-factor and the double-factor safety control taking both vibration velocity and vibration frequency into consideration are comprehensively analyzed, and the weaknesses of the application scopes of both criteria in the safety performance evaluation of blasting vibration are discussed. Relative researches on the duration time of blasting are introduced, and the duration time for blasting is proposed to be embraced in the scope of safety control. Besides, the research progresses of safety control of water shock wave and aerial shock wave are, respectively, introduced, and the weaknesses of the above methods in the application to underwater blasting engineering are analyzed. Based on the analysis of the adverse effects of seismic wave and shock wave, the new idea to study the synergistic effects of both kinds of waves is put forward, and the comprehensive safety control method which includes both seismic wave and shock wave remains to be developed.