An investigation on the dynamics of domain switching of Bi0.5Na0.5TiO3-based ferroelectric ceramics

Zhipeng Gao,Hang Zhang,Yi Liu,Lingfeng Wu,Jia Yang,Tao Zhang,Haiyan Wang,Xuefeng Chen,Genshui Wang,Hongliang He 한국물리학회 2017 Current Applied Physics Vol.17 No.4

The dynamics of domain switching of Bi0.5Na0.5TiO3-based ferroelectric ceramic was investigated. With the electric field increasing, the domain switch experienced three sections of no domain switch region, creep region and flow region. In the creep region, the domain switch is dominated by the thermally activated domain wall movement. In flow region, the domain wall experience the viscous flow motion. For the BNT-BA-Zn ceramic, the activation energy of creep domain switch is much higher than it in flow region. With temperature increasing, the sensitivity of domain wall motion to the frequency is decreasing. This result demonstrated the domain switch of different ferroelectric materials could be quantitatively analyzed and compared based on the simple polarization - current - electric field data.

Efficiently targeted therapy of glioblastoma xenograft via multifunctional biomimetic nanodrugs

Zhipeng Yao,Xiaochun Jiang,Hong Yao,Yafeng Wu,Fan Zhang,Cheng Wang,Chenxue Qi,Chenhui Zhao,Zeyu Wu,Min Qi,Jia Zhang,Xiaoxiang Cao,Zhichun Wang,Fei Wu,Chengyun Yao,Songqin Liu,Shizhang Ling,Hongping Xi 한국생체재료학회 2022 생체재료학회지 Vol.26 No.4

Background: Glioblastoma multiforme (GBM) is a fatal malignant primary brain tumor in adults. The therapeutic efficacy of chemotherapeutic drugs is limited due to the blood-brain barrier (BBB), poor drug targeting, and short biological half-lives. Multifunctional biomimetic nanodrugs have great potential to overcome these limitations of chemotherapeutic drugs. Methods: We synthesized and characterized a biomimetic nanodrug CMS/PEG-DOX-M. The CMS/PEG-DOX-M effectively and rapidly released DOX in U87 MG cells. Cell proliferation and apoptosis assays were examined by the MTT and TUNEL assays. The penetration of nanodrugs through the BBB and anti-tumor efficacy were investigated in the orthotopic glioblastoma xenograft models. Results: We showed that CMS/PEG-DOX-M inhibited cell proliferation of U87 MG cells and effectively induced cell apoptosis of U87 MG cells. Intracranial antitumor experiments showed that free DOX hardly penetrated the BBB, but CMS/PEG-DOX-M effectively reached the orthotopic ntracranial tumor through the BBB and significantly inhibited tumor growth. Immunofluorescence staining of orthotopic tumor tissue sections confirmed that nanodrugs promoted apoptosis of tumor cells. This study developed a multimodal nanodrug treatment system with the enhanced abilities of tumor-targeting, BBB penetration, and cancer-specific accumulation of chemotherapeutic drugs by combining chemotherapy and photothermal therapy. It can be used as a flexible and effective GBM treatment system and it may also be used for the treatment of other central nervous systems (CNS) tumors and extracranial tumors.

Ordered Arrays of Vertically Aligned [110] Silicon Nanowires by Suppressing the Crystallographically Preferred Etching Directions

Huang, Zhipeng,Shimizu, Tomohiro,Senz, Stephan,Zhang,Zhang, Xuanxiong,Lee, Woo,Geyer, Nadine,Gö,sele, Ulrich American Chemical Society 2009 NANO LETTERS Vol.9 No.7

<P>The metal-assisted etching direction of Si(110) substrates was found to be dependent upon the morphology of the deposited metal catalyst. The etching direction of a Si(110) substrate was found to be one of the two crystallographically preferred 100 directions in the case of isolated metal particles or a small area metal mesh with nanoholes. In contrast, the etching proceeded in the vertical [110] direction, when the lateral size of the catalytic metal mesh was sufficiently large. Therefore, the direction of etching and the resulting nanostructures obtained by metal-assisted etching can be easily controlled by an appropriate choice of the morphology of the deposited metal catalyst. On the basis of this finding, a generic method was developed for the fabrication of wafer-scale vertically aligned arrays of epitaxial [110] Si nanowires on a Si(110) substrate. The method utilized a thin metal film with an extended array of pores as an etching catalyst based on an ultrathin porous anodic alumina mask, while a prepatterning of the substrate prior to the metal depostion is not necessary. The diameter of Si nanowires can be easily controlled by a combination of the pore diameter of the porous alumina film and varying the thickness of the deposited metal film.</P>

Color Adjustment Based on Support Vector Regression for Multi-View Video

Huadong Sun,Xuesong Jin,Zhipeng Fan,Lizhi Zhang,Qian Wu 보안공학연구지원센터 2015 International Journal of Multimedia and Ubiquitous Vol.10 No.1

Significant color discrepancies between the different camera views can be observed in multi-view video sequences. In this paper, a color adjustment algorithm based on support vector regression is proposed. A mapping function is established by extracted feature points from original-image and target-image. Then the mapping function is applied to the original image to obtain the corrected image. Experimental results show that the proposed method can produce good correction result. It also shows that the color differences between multi-view video can be effectively reduced by SVR.

Evolution and recovery of original total organic carbon for muddy source rocks with different total organic carbon in the Western Sichuan Depression, Sichuan Basin, China

Zhipeng Huo,Yan Gao,Yi Zhao,Tianyu Zheng,Jinchuan Zhang,Jianghui Ding 한국지질과학협의회 2019 Geosciences Journal Vol.23 No.1

According to the new quantitative model for original total organic carbon (TOCo) evolution and recovery of source rocks, The TOCo evolution of muddy source rocks with different TOCs (MSRDTOC) (0.5% < TOC ≤ 1.5%, 2.5% < TOC ≤ 3.5% and 4.0% < TOC ≤ 6.0%, and their average values were 1.0%, 3.0% and 5.0%, respectively) and type III kerogen were investigated in the Western Sichuan Depression (WSD) of Sichuan Basin, China, finally recovery coefficients of TOCo were calculated. Studies showed that TOCo evolution of the MSRDTOC have similarities and differences. The similarities reveal that with the increase of thermal evolution level, varied TOC all reduce gradually and the sharp reduction occurs at the stage of a large number of hydrocarbon generation and expulsion (0.7% ≤ vitrinite reflectance (VR) ≤ 1.3%). The differences indicate that the starting time and decrease range for varied TOC are different. For TOCo = 1.0%, 3.0% and 5.0%, their starting time of TOC reduction are VR = 1.05%, 0.80% and 0.60%, respectively. When VR reaches to 3.0%, their TOC decrease ranges are 30.54%, 38.52% and 44.00% and their recovery coefficients are 1.44, 1.63 and 1.79, respectively. The higher the TOC is, the earlier the starting time of TOC reduction is, the bigger the range of TOC reduction and recovery coefficient are. It must restore TOCo when we evaluate source rocks at high-over mature stage and predict oil and gas resources. The MSRDTOC and their TOCo recovery should be evaluated, respectively.

A negative stiffness inerter system (NSIS) for earthquake protection purposes

Zhipeng Zhao,Qingjun Chen,Ruifu Zhang,Yiyao Jiang,Chao Pan 국제구조공학회 2020 Smart Structures and Systems, An International Jou Vol.26 No.4

The negative stiffness spring and inerter are both characterized by the negative stiffness effect in the force-displacement relationship, potentially yielding an amplifying mechanism for dashpot deformation by being incorporated with a series tuning spring. However, resisting forces of the two mechanical elements are dominant in different frequency domains, thus leading to necessary complementarity in terms of vibration control and the amplifying benefit. Inspired by this, this study proposes a Negative Stiffness Inerter System (NSIS) as an earthquake protection system and developed analytical design formulae by fully utilizing its advantageous features. The NSIS is composed of a sub-configuration of a negative stiffness spring and an inerter in parallel, connected to a tuning spring in series. First, closed-form displacement responses are derived for the NSIS structure, and a stability analysis is conducted to limit the feasible domains of NSIS parameters. Then, the dual advantageous features of displacement reduction and the dashpot deformation amplification effect are revealed and clarified in a parametric analysis, stimulating the establishment of a displacement-based optimal design framework, correspondingly yielding the design formulae in analytical form. Finally, a series of examples are illustrated to validate the derived formulae. In this study, it is confirmed that the synergistic incorporation of the negative stiffness spring and the inerter has significant energy dissipation efficiency in a wide frequency band and an enhanced control effect in terms of the displacement and shear force responses. The developed displacement-based design strategy is suitable to utilize the dual benefits of the NSIS, which can be accurately implemented by the analytical design formulae to satisfy the target vibration control with increased energy dissipation efficiency.

Variational nodal methods for neutron transport: 40 years in review

Zhang Tengfei,Li Zhipeng 한국원자력학회 2022 Nuclear Engineering and Technology Vol.54 No.9

The variational nodal method for solving the neutron transport equation has evolved over 40 years. Based on a functional form of the Boltzmann neutron transport equation, the method now comprises a complete set of variants that can be employed for different problems. This paper presents an extensive review of the development of the variational nodal method. The emphasis is on summarizing the whole theoretical system rather than validating the methodologies. The paper covers the variational nodal formulation of the Boltzmann neutron transport equation, the Ritz procedure for various application purposes, the derivation of boundary conditions, the extension for adjoint and perturbation calculations, and treatments for anisotropic scattering sources. Acceleration approaches for constructing response matrices and solving the resulting system of algebraic equations are also presented

Analytical evaluation of the influence of vertical bridge deformation on HSR longitudinal continuous track geometry

Zhipeng Lai,Lizhong Jiang,Xiang Liu,Yuntai Zhang,Tuo Zhou 국제구조공학회 2022 Steel and Composite Structures, An International J Vol.44 No.4

A high-speed railway (HSR) bridge may undergo long-term deformation due to the degradation of material stiffness, or foundation settlement during its service cycle. In this study, an analytical model is set up to evaluate the influence of this longterm vertical bridge deformation on the track geometry. By analyzing the structural characteristics of the HSR track-bridge system, the energy variational principle is applied to build the energy functionals for major components of the track-bridge system. By further taking into account the interlayer’s force balancing requirements, the mapping relationship between the deformation of the track and the one of the bridge is established. In order to consider the different behaviors of the interlayers in compression and tension, an iterative method is introduced to update the mapping relationship. As for the validation of the proposed mapping model, a finite element model is created to compare the numerical results with the analytical results, which show a good agreement. Thereafter, the effects of the interlayer’s different properties of tension and compression on the mapping deformations are further evaluated and discussed.

Durable N-halamine Antibacterial Cellulose Based on Thiol-ene Click Chemistry

Zhipeng Ma,Maoli Yin,Mengshuang Zhang,Zhenming Qi,Xuehong Ren,Tung-Shi Huang 한국섬유공학회 2019 Fibers and polymers Vol.20 No.2

Antibacterial cotton fabrics were prepared with 3-allyl-5,5-dimethylhydantoin (ADMH) by UV photoinitiated thiol-ene click chemistry after 3-mercaptopropyltriethoxysilane (MPTES) was introduced on the surface of cotton fabrics. The treated cotton fabrics were characterized by SEM, FT-IR and EDS. After chlorination with diluted sodium hypochlorite, the treated samples showed good antibacterial efficacy against S. aureus and E. coli O157:H7. About 106 of S. aureus and E. coli O157:H7 could be completely inactivated within 1 min and 5 min of contact, respectively. Compared to the control samples, the antibacterial treatment method used in this study only had a minor effect on the tensile strength of cotton fabrics. Besides, the treated cotton fabrics showed good storage stability and 77 % of the active chlorine remained after 30 days. After exposure to bleach solution, almost all of the active chlorine was restored. The prepared antimicrobial cotton fabrics showed good washing and UV light stability.

Thermo-electro-mechanical vibration and buckling analysis of a functionally graded piezoelectric porous cylindrical microshell

Zhipeng Lyu,Wenguang Liu,Chao Liu,Yuhang Zhang,Mengxiang Fang 대한기계학회 2021 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.35 No.10

In this paper, the vibration and buckling behavior of a functionally graded piezoelectric porous cylindrical microshell under thermo-electro-mechanical loads are explored on the basis of modified couple stress theory and higher-order shear deformation theory. First, the model of a functionally graded piezoelectric porous cylindrical microshell composed of piezoelectric materials with gradient change in the thickness direction was described. Second, the governing equations of the microshell were derived by Hamilton's principle and Maxwell equation. Third, the modal frequency and buckling equations of the microshell with simply supported ends were obtained on the basis of harmonic trigonometric functions. Finally, the effects of parameters on the modal frequency and buckling behavior were carried out by case studies. The results show that the modal frequency of the microshell can be adjusted by changing the porosity volume fraction, power index, applied voltage, axial load and geometric dimensions. It is also found that the vibration of the microshell is suppressed by positive voltage and axial compression but is strengthened by negative voltage and axial tension, and the material length scale parameter increases stiffness. In addition, the effects of applied voltage and axial load on the buckling behavior are larger than those of temperature. Results can be used to guide the design and application of piezoelectric devices.