Aqueous Processing and Effects of V2O5 on Microwave Dielectric Properties of Multilayer Li1.075Nb0.625Ti0.45O3 Ceramics

Shaochun Li,Yongjuan Geng,Tiejun Zhao,Zuquan Jin,Peng Zhang 대한금속·재료학회 2014 ELECTRONIC MATERIALS LETTERS Vol.10 No.1

In the present work, we report the development of an aqueous tape casting method and a low temperature co-firing process for fabrication of multilayer Li1.075Nb0.625Ti0.45O3 microwave dielectric ceramics. A co-binder, consisting of polyvinyl acetate latex (PVAc) and polyvinyl alcohol (PVA), was used to prepare aqueous Li1.075Nb0.625Ti0.45O3 tapes. PVA addition increased the tape flexibility and adhesiveness but resulted in decreased tensile strength. Rheological tests indicated that the aqueous ceramic slurry exhibited a typical shear thinning behavior without thixotropy, suitable for tape casting. Scanning electron microscopy (SEM) studies revealed that the green tapes have a defect-free surface and that the multilayer ceramics sintered at 900°C have a fine plate like, grainy microstructure of uniform size. At lower temperatures, increased densification rates were achieved by addition of V2O5 to Li1.075Nb0.625Ti0.45O3 ceramics. The saturated bulk densities and dielectric constants (εr) of Li1.075Nb0.625Ti0.45O3 multilayer ceramics affected by lower sintering temperatures with an increase in V2O5 doping, and then an improvement in the quality factor (Q × f value) of the samples was achieved at the lower sintering temperatures. As a result, the εr of 64.9 and the Q × f value of 8800 GHz were obtained in the sample with an addition of 3 wt. % V2O5, sintered at a temperature of 900°C. No reaction was observed between the ceramic and silver layers when sliver inner-electrode, was sintered with ceramic tapes at 900°C.

Preparation and Dieletrical Properties of Li1.075Nb0.625Ti0.45O3 Powders by Hydrothermal Method

Shaochun Li,Yongjuan Geng,Tiejun Zhao,Peng Zhang 대한금속·재료학회 2012 ELECTRONIC MATERIALS LETTERS Vol.8 No.4

A hydrothermal method has been developed and shown to be effective for the preparation of Li1.075Nb0.625Ti0.45O3(LNT) nano-particles. Hydrothermal reaction temperature was in the range from 120°C - 200°C. The crystalline structure and morphology of the prepared particles have been characterized by x-ray diffraction and scanning electron microscopy. Results indicate that hydrothermal temperature had a great effect on the phase formation and morphology of the particles. The prepared powders crystallized at 140°C, and the pure LNT phase was formed at 180°C. The size of LNT particles increased with increasing reaction temperature, and plate-like LNT particles with thickness of 15 - 30 mm and a diameter of 80 - 200 mm were obtained at 200°C. It was found that LNT powders synthesized at 180°C gave the LNT ceramics the highest microwave dielectric properties (εr = 66, Q×f = 8946 GHz) due to good crystallization and low particle size.

Dexmedetomidine targets miR-146a and participates in the progress of chronic obstructive pulmonary disease in vivo and in vitro

Li Na,Li Shuangfeng,Wu Yehua,Xiong Lu,Li Tiejun,Xing Dandan,Li Qiuchang,Wu Duozhi 한국유전학회 2021 Genes & Genomics Vol.43 No.12

Background Chronic obstructive pulmonary disease (COPD) is a chronic lung disease and the third leading cause of death in the world. Dexmedetomidine has been reported to efectively inhibit histamine-induced bronchoconstriction. However, the molecular mechanism of dexmedetomidine in COPD has not been found. Objective To explore the role and mechanism of dexmedetomidine in COPD, and to provide theoretical basis for clinical treatment of COPD. Methods The expression of miR-146a was regulated by mimics or inhibitor and the relative expression of apoptotic proteins p53, Bax and Bcl-2 in human bronchial epithelial 16HBE cells was determined by real-time PCR and Western blot. Dexmedetomidine was treated for 16HBE cells and alveolar epithelial type II cells (AEC2), the cell apoptosis was detected by TUNEL and Hoechst33342 staining. A COPD rat model was established by smoking to test the efects of dexmedetomidine on the progression of COPD. The levels of IL-6, IL-1β and TNF-α in serum were measured by ELISA and the protein concentration of bronchoalveolar lavage fuid (BALF) was also detected in dexmedetomidine treated COPD rat model. Results miR-146a promoted 16HBE cell apoptosis and reduced cell proliferation. Additionally, dexmedetomidine was showed to reduce the 16HBEL cell apoptosis through reducing the expression of miR-146a. Moreover, dexmedetomidine regulated cell apoptosis and cell apoptosis through miR-146a in AEC2 cells. More importantly, dexmedetomidine attenuated the morphology and pathology of COPD rat model. Conclusion Dexmedetomidine reduced 16HBE cells and AEC2 cell apoptosis and attenuated COPD by down-regulating miR-146a.

Steel scale-CaO composite catalyst for coke combustion and in-situ NO and SO2 removal

Li Zhang,Jingchong Yan,Zhiping Lei,Xianzhong Cao,Tiejun Chun,Zhanku Li,Hengfu Shui,Shibiao Ren,Zhicai Wang,Ying Kong 한국공업화학회 2022 Journal of Industrial and Engineering Chemistry Vol.110 No.-

The performance of the steel scale (SS)-CaO composite on the combustion of coke nuts and in-situ reductionof SO2 and NO emission was investigated. Combustion experiments show that SS-CaO compositeaccelerates coke combustion and reduces SO2 and NO emissions concurrently. X-ray diffraction (XRD),scanning electron microscopy (SEM), and electron spin resonance (ESR) were used to investigate thecatalysis mechanism. Results show that SS and CaO have synergistic effect in in-situ denitration. Theincrease of SS and CaO fraction in the composites improve the denitration and sulfur fixation performance,respectively. The denitration activity is mainly attributed to the Fe2O3 in SS and Ca2Fe2O5 formedduring combustion. The desulfurization is due to the sulfur fixation with CaO. The increasing fraction ofCaO in the composites leads to the agglomeration of ash particles. 2%CaO is confirmed as the optimumaddition for catalytic combustion and emission reduction. This work sheds light on the cheap and effectivecatalysts that are potentially useful for iron ore sintering.

Secret Sharing-Based Chaotic Image Encryption

Tiejun Zhang,Aya El-Fatyany,Li Li,Mohamed Amin,Ahmed A. Abd El-Latif 보안공학연구지원센터 2015 International Journal of Security and Its Applicat Vol.9 No.7

This paper presents an image encryption scheme for secure digital images based on secret sharing and coupled map lattices. In this scheme, the secret image is encrypted before the sharing phase based on key sequences generated by chaotic map lattices. Experimental results and analysis show that the proposed scheme has better security and can be easily protects both confidentiality and loss-tolerance simultaneously in shadow images.

The Influence of Non-synchronous Excavation of Twin Curved Shield Tunnels

Shaohua Li,Changfu Huang,Tiejun Yao,Pengfei Li 대한토목학회 2022 KSCE JOURNAL OF CIVIL ENGINEERING Vol.26 No.5

The theoretical model of twin curved shield tunnels and refined numerical model considering the characteristics of wedge-shaped segment ring joints were established in this paper. Two construction schemes of taking the inner side or outer side of the twin curved tunnels as the first tunnel were conducted for comparison. Then two main characteristics of curved tunnel construction (over-excavation and yaw excavation loadings) were taken as variables to explore their response to the approaching construction caused by unsynchronized driving of twin curved shield tunnels. The ground surface settlement troughs obtained by the analytical solution and numerical simulation are in good agreement with the monitoring result. On the condition that the curved tunnel at the inner side is taken as the first tunnel, the excavation will intensify the ground settlement and the internal forces of its segment. In the case that the overcutting gap is not of large volume, it is advisable to first excavate the curved tunnel at the outer side, and then construct the curved tunnel at the inner side. The influence of soil loss on the ground disturbance is greater than that of construction loadings. The excessive overcutting gap not only easily induces a sharp increase in the ground vertical displacement, but also may lead to the movement of soil at the inner and middle sides towards the inner side of the curved tunnels, and causes the soil at the outer side to move towards the outer side of the curved tunnels. Remarkably, excessive overcutting gap may lead to large horizontal displacements of the ground surface.

Resonance Elastic Scattering and Interference Effects Treatments in Subgroup Method

Li, Yunzhao,He, Qingming,Cao, Liangzhi,Wu, Hongchun,Zu, Tiejun Korean Nuclear Society 2016 Nuclear Engineering and Technology Vol.48 No.2

Based on the resonance integral (RI) tables produced by the NJOY program, the conventional subgroup method usually ignores both the resonance elastic scattering and the resonance interference effects. In this paper, on one hand, to correct the resonance elastic scattering effect, RI tables are regenerated by using the Monte Carlo code, OpenMC, which employs the Doppler broadening rejection correction method for the resonance elastic scattering. On the other hand, a fast resonance interference factor method is proposed to efficiently handle the resonance interference effect. Encouraging conclusions have been indicated by the numerical results. (1) For a hot full power pressurized water reactor fuel pin-cell, an error of about +200 percent mille could be introduced by neglecting the resonance elastic scattering effect. By contrast, the approach employed in this paper can eliminate the error. (2) The fast resonance interference factor method possesses higher precision and higher efficiency than the conventional Bondarenko iteration method. Correspondingly, if the fast resonance interference factor method proposed in this paper is employed, the $k_{inf}$ can be improved by ~100 percent mille with a speedup of about 4.56.

Media-aware quantitative trading based on public Web information

Li, Qing,Wang, Tiejun,Gong, Qixu,Chen, Yuanzhu,Lin, Zhangxi,Song, Sa-kwang Elsevier 2014 Decision Support Systems Vol.61 No.-

DDAB-MODIFIED TPGS-b-(PCL-ran-PGA) NANOPARTICLES AS ORAL ANTICANCER DRUG CARRIER FOR LUNG CANCER CHEMOTHERAPY

TIEJUN ZHAO,HEZHONG CHEN,LIXIN YANG,HAI JIN,ZHIGANG LI,LIN HAN,FANGLIN LU,ZHIYUN XU 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2013 NANO Vol.8 No.2

Oral chemotherapy is a great way to cancer treatment because it is less stressful being that the patient will have less hospital visits and can still maintain a close relationship with health care professionals. In this research, three types of nanoparticle formulation from commercial PCL and self-synthesized TPGS-b-(PCL-ran-PGA) diblock copolymer were fabricated for oral delivery of antitumor agents, including DDAB-modified PCL nanoparticles, unmodified TPGS-b-(PCL-ran-PGA) nanoparticles and DDAB-modified TPGS-b-(PCL-ran-PGA) nanoparticles. Firstly, the TPGS-b-(PCL-ran-PGA) diblock copolymer was synthesized and characterized. DDAB was adopted to increase retention time at the cell surface, thus increasing the chances of nanoparticle uptake by the gastrointestinal mucosa and improving drug absorption. The TPGS-b-(PCL-ran-PGA) nanoparticles were found by FESEM of spherical shape and around 200 nm in diameter. The surface charge of TPGS-b-(PCL-ran-PGA) nanoparticles was reversed from anionic to cationic after DDAB modification. The DDAB-modified TPGS-b-(PCL-ran-PGA) nanoparticles have significantly higher level of the cell uptake than that of DDAB-modified PCL nanoparticles and unmodified TPGS-b-(PCL-ran-PGA) nanoparticles. In vitro cell viability studies showed advantages of the DDAB-modified TPGS-b-(PCL-ran-PGA) nanoparticles over Taxotere® in terms of cytotoxicity against A549 cells. In conclusion, oral chemotherapy by DDAB-modified TPGS-b-(PCL-ran-PGA) nanoparticle formulation may provide a promising outcome for lung cancer patients.

An integrated biomass-derived syngas/dimethyl ether process

Tiejun Wang,Jie Chang,Yan Fu,Qi Zhang,Yuping Li 한국화학공학회 2007 Korean Journal of Chemical Engineering Vol.24 No.1

Cu-Zn-Al methanol catalyst combined with HZSM-5 was used for dimethyl ether (DME) synthesis froma biomass-derived syngas containing nitrogen. The syngas was produced by air-steam gasification of pine sawdust ina bubbling fluidized bed biomass gasifier with a dry reforming reaction over ultra-stable NiO-MgO catalyst packedin a downstream reactor for stoichiometric factor (H2, CO, CO2) adjustment. It constantly gave syngas with H2/CO ratioof 1.5 and containing trace CH4 and CO2 during a period of 150 h. The obtained N2-containing biomass-derived syngas% CO per-pass conversion and 66.7% DME selectivity could be achievedunder the condition of 533 K, 4 MPa and 1,000-4,000 h1. The maximized DME yield, 244 g DME/Kgbiomass (dry basis),was achieved under a gasification temperature of 1,073 K, ER (Equivalence Ratio) of 0.24, S/B (Steam to BiomassRatio) of 0.72 and reforming temperature of 1,023 K with the addition of 0.54 Nm3 biogas/Kgbiomass (dry basis).