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Mechanism of shear strength deterioration of loess during freeze-thaw cycling
Xu, Jian,Wang, Zhangquan,Ren, Jianwei,Yuan, Jun Techno-Press 2018 Geomechanics & engineering Vol.14 No.4
Strength of loess that experienced cyclic freeze and thaw is of great significance for evaluating stability of slopes and foundations in loess regions. This paper takes the frequently encountered loess in the Northwestern China as the study object and carried out three kinds of laboratory tests including freeze-thaw test, direct shear test and SEM test to investigate the strength behaviors of loess after cyclic freeze and thaw, and the correlation with meso-level changes in soil structure. Results show that for loess specimens at four dry densities, the cohesion decreases with freeze-thaw cycles until a residual value is reached and thus an exponential equation is proposed. Besides, little change in the angle of internal friction was observed as freeze-thaw proceeds. This may depend on the varying of soil structure, based on which a clue can be found from the surface morphology and mesoscopic scanning of loess specimens. Clearly we observed significant changes in surface morphology of loess and it tends to aggravate at higher water contents or more cycles of freeze and thaw. Moreover, freeze-thaw cycling leads to obvious changes in the meso-structure of loess including lowering the particle aggregates and increasing both the proportion of fine particles and porosity area ratio. A damage variable dependent on the ratio of porosity area is introduced based on the continuum damage mechanics and its correlation with cohesion is discussed.
Wang, Jianwei,Ren, Yingchun,Xu, Sheng,Mi, Puke Techno-Press 2017 Advances in materials research Vol.6 No.3
In this article, novel olefin polymerization catalyst with lower cost and simple synthetic process were developed, $ArOTiCl_3$ complexes [$(2-OMeC_6H_4O)TiCl_3(C1)$, $(2,4-Me_2C_6H_3O)TiCl_3(C2)$, $TiCl_3(1,4-OC_6H_4O)TiCl_3(C3)$, $TiCl_3(1,4-OC_6H_2O-Me_2-2,5)$ $TiCl_3(C4)$] and corresponding $(ArO)_2TiCl_2$ complexes [$TiCl_2(OC_6H_4-OMe-2)_2(C5)$ and $TiCl_2(OC_6H_3-Me_2-2,6)_2(C6)$] have been synthesized by the reaction of $TiCl_4$ with phenol, all these complexes were well characterized with $^1H$ NMR, $^{13}C$ NMR, MASS and EA. When combined with methylaluminoxane (MAO), the $ArOTiCl_3/MAO$ system shows high activity for ethylene copolymerization with 1-octene and copolymer was obtained with broaden molecular weight distribution (MWD). The $^{13}C$ NMR result of polymer indicates that the 1-octene incorporation in polymer reached up to 8.29 mol%. The effects of polymerization temperature, concentration of polymerization monomer and polymerization time on the catalytic activity have been investigated.
Siqi Xu,Xiaoyan Wu,Zhihua Tao,Hongsheng Li1,Chenliang Fan,Songjin Chen,Jianwei Guo,Yao Ning,Xuqi Hu 한국유전학회 2020 Genes & Genomics Vol.42 No.3
Background Androgen-independent prostate cancer (AIPC) is an extremely malignant tumor developed from the androgen dependent (ADPC). However, the mechanism of transition process from ADPC to AIPC remains unknown. Objective Here we aimed to identify the androgen receptor (AR) target gene and its roles in AIPC. Methods Target genes of AR were identified by ChIP-seq in AIPC cells. AR target gene PCDH7 was detected by real time PCR and western blot. Methylation of PCDH7 was measured by bisulfite sequencing and bisulfite amplicon sequencing. Cell growth, invasion and apoptosis were measured by CCK-8, transwell and flow cytometry, respectively. Results AR was significantly enriched in the upstream of PCDH7 gene. The expression of PCDH7 was significantly decreased, while the methylation of PCDH7 was increased in the AIPC cells compared to the ADPC cells. DNA methyltransferase inhibitor significantly suppressed the methylation and increased the mRNA and protein level of PCDH7. Moreover, overexpression of DNMT1 remarkably reduced the mRNA and protein level of PCDH7. DNA methyltransferase inhibitor decreased the cell growth and invasion while promote the cell apoptosis in the AIPC cells. AR significantly target PCDH7, whose hypermethylation may repress cell growth and invasion, and promote apoptosis in AIPC. Conclusions This study might provide a novel potential target for the treatment of AIPC.
Tianshu Xu,Jianwei Xia,Xiao-Na Song,Zhen Wang,Hua-Sheng Zhang 제어·로봇·시스템학회 2021 International Journal of Control, Automation, and Vol.19 No.2
In this paper, the topic of sampled-data based dissipativity control for Takagi-Sugeno (T-S) fuzzy Markovian jump systems with incomplete transition rates and actuator saturation is addressed. First of all, by constructing an appropriate two-sided closed-loop function that captures the realistic information of sampling pattern, together with the free-matrix-based inequality approach, a sufficient condition is developed to ensure the considered systems to be strictly(Q,S,R)-γ-dissipative. Then, the corresponding mode-dependent sampled-data controllers are designed based on the given dissipativity condition. As a corollary, the controller design is presented for the system without disturbance. Furthermore, an optimization problem is investigated in order to maximize the domain of the attraction. Finally, simulation examples are offered to verify the feasibility of the results.
Highly efficient and ultra-rapid adsorption of malachite green by recyclable crab shell biochar
Jia Wu,Jianwei Yang,Pu Feng,Lishan Wen,Guohuan Huang,Chuanhui Xu,Baofeng Lin 한국공업화학회 2022 Journal of Industrial and Engineering Chemistry Vol.113 No.-
In this study, waste crab shell was hydrothermally carbonized and then activated to prepare an effectiveand recyclable adsorbent. The adsorption performance of the adsorbent for different dyes was investigatedthrough adsorption experiments, and the results showed that it had the largest adsorption performancefor malachite green. Furthermore, the adsorption performance and mechanism of malachite greenwere investigated by static and dynamic adsorption method. The crab shell biochar could remove6142.5 mg g1 of malachite green within 3 minutes, indicating that the crab shell biochar could ultrarapidand highly efficient adsorb malachite green. In addition, the malachite green adsorbed on the crabshell biochar could be removed by calcination, which achieved the entire regeneration of the crab shellbiochar. The adsorption of malachite green by crab shell biochar adsorbent conformed to the pseudosecond-order kinetic model, the Dubinin-Radushkevich and Langmuir isotherm adsorption model. Physical and chemical characterization indicated that the adsorption mechanism of malachite greenincluded alkaline fading effect, hydrogen bonding and p-p interaction.
Controllable tuning of the electronic transport in pre-designed graphene nanoribbon
Hui Zeng,Jun Zhao,Jianwei Wei,Dahai Xu,J.-P. Leburton 한국물리학회 2012 Current Applied Physics Vol.12 No.6
We make use of ab initio density functional theory calculation to explore the electronic and transport properties of zigzag-edged graphene nanoribbon (ZGNR) with peculiar designed electronic transport channels by tailoring the atomic configuration of the nanostructure. Tailoring the atomic structure has significant influences on the electronic transport of the defective nanostructure, and eventually the metal-semiconducting transition are identified with the increasing number of missing atoms. Our results demonstrate that pre-designed graphene nanoribbon by selective tailoring with high precision is expected to be served as the basic component for nanoelectronic device.
Autophagy of bovine mammary epithelial cell induced by intracellular Staphylococcus aureus
Na Geng,Kangping Liu,Jianwei Lu,Yuliang Xu,Xiaozhou Wang,Run Wang,Jianzhu Liu,Yongxia Liu,Bo Han 한국미생물학회 2020 The journal of microbiology Vol.58 No.4
Bovine mastitis is a common disease in the dairy industry that causes great economic losses. As the primary pathogen of contagious mastitis, Staphylococcus aureus (S. aureus) can invade bovine mammary epithelial cells, thus evading immune defenses and resulting in persistent infection. Recently, autophagy has been considered an important mechanism for host cells to clear intracellular pathogens. In the current study, autophagy caused by S. aureus was detected, and the correlation between autophagy and intracellular S. aureus survival was assessed. First, a model of intracellular S. aureus infection was established. Then, the autophagy of MAC-T cells was evaluated by confocal microscopy and western blot. Moreover, the activation of the PI3K-Akt-mTOR and ERK1/2 signaling pathways was determined by western blot. Finally, the relationship between intracellular bacteria and autophagy was analyzed by using autophagy regulators (3-methyladenine [3-MA], rapamycin [Rapa] and chloroquine [CQ]). The results showed that S. aureus caused obvious induction of autophagosome formation, transformation of LC3I/II, and degradation of p62/SQSTM1 in MAC-T cells; furthermore, the PI3K-Akt-mTOR and ERK1/2 signaling pathways were activated. The number of intracellular S. aureus increased significantly with autophagy activation by rapamycin, whereas the number decreased when the autophagy flux was inhibited by chloroquine. Therefore, this study indicated that intracellular S. aureus can induce autophagy and utilize it to survive in bovine mammary epithelial cells.