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Stability analysis for a second-order continuous finite-time control system subject to a disturbance

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控制理论与应用（英文版） 2009年第3期7卷 271-276页

作者： Shihong DING Shihua li qi li School of Automation Southeast University Nanjing Jiangsu 210096 China

In this paper, using finite-time control method, we consider the disturbance analysis of a second-order system with unknown but bounded disturbance. We show that the states of the second-order system will be stabilized to a region containing the origin. The radius of this region is determined by the control parameters and can be rendered as small as desired. The rigorous stability analysis is also given. Compared with the conventional PD control law, the finite-time control law yields a better disturbance rejection performance. Numerical simulation results show the effectiveness of the method.

关键词： Finite-time control Second-order system Disturbance analysis Bounded disturbance

Effect of Extrusion Forming on Compressive Strength of Al_(18)B_4O_(33)w/Mg Composites

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稀有金属材料与工程 2009年第A3期38卷 41-44页

作者： li Zhengjia li Hejun qi Lehua Oy Haibo Northwestern Polytechnical University Xi＇an 710072 China

The aluminum borate whisker reinforced magnesium matrix composites (Al18B4O33w/Mg) were fabricated by pressure infiltration technique and extrusion-vacuum infiltration technique respectively to study the effect of extrusion forming on their mechanical behaviors. The microstructure of the composites was observed by scanning electron microscopy. The compressive strength was investigated and compared with that of the matrix alloy AZ91D. The results show that the extrusion forming could cause fracture of the whisker, but reduce the holes in the composite during impregnation and improve the interfacial bonding between the whisker and the matrix alloy. Compared with that of the matrix as-cast alloy AZ91D, the compressive strength of Al18B4O33w/Mg by the pressure infiltration technique was increased by 22%, while that of Al18B4O33w/Mg by the extrusion-vacuum infiltration technique was increased by 120 %.

关键词：硼酸铝复合材料电子显微镜抗压强度

Biotic Homogenization Caused by the Invasion of Solidago canadensis in China

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Journal of Integrative Agriculture 2013年第5期12卷 835-845页

作者： CHEN Guo-qi ZHANG Chao-bin MA ling qiANG Sheng John ASilander li li qi Weed Research Laboratory Nanjing Agricultural University Department of Ecology and Evolutionary Biology University of Connecticut Northern Crop Science Laboratory USDA-ARS

Although studies argue that invasive species can cause biotic differentiation, some cases show that biological invasions actually decrease biodiversity through biotic homogenization. The concept of biotic homogenization through the invasion of a certain serious invasive plant species merit more studies. Hence, we used field surveys to quantitatively compare invasive populations of Solidago canadensis （SC） in China with the control sites （adjacent sites to SC present sites yet without the species） and SC native populations in the USA. We found that plant communities in SC invaded habitats shared similarities with those in SC native ranges. Bray-Curtis similarity clearly showed that the composition of plant communities in SC invaded habitats were similar to those in SC native ranges. Both in the native and introduced range, plant communities with SC present were characterized by SC being dominant, significantly lower species richness, or-diversity and p-diversity, as well as a decrease in the correlation coefficient between geographic distance and floristic similarities. SC favors fertile and moist loam habitat, while it dominated in various habitats in China, where more than 20 different dominants should have occurred. In conclusion, serious invasive species can quickly remodel and homogenize diverse communities by dominating them.

关键词： biodiversity control site field survey geographic distance invasive population native population similarity

Aircraft noise exposure affects rat behavior,plasma norepinephrine levels,and cell morphology of the temporal lobe

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Journal of Zhejiang University-Science B(Biomedicine & Biotechnology) 2011年第12期12卷 969-975页

作者： Guo-qing DI Bing ZHOU Zheng-guang li qi-li liN Institute for Environmental Pollution Control Technology Zhejiang University Hangzhou 310058 China

In order to investigate the physiological effects of airport noise exposure on organisms,in this study,we exposed Sprague-Dawley rats in soundproof chambers to previously recorded aircraft-related noise for 65 *** comparison,we also used unexposed control *** was arranged according to aircraft flight schedules and was adjusted to its weighted equivalent continuous perceived noise levels(LWECPN) of 75 and 80 dB for the two experimental *** examined rat behaviors through an open field test and measured the concentrations of plasma norepinephrine(NE) by high performance liquid chromatography-fluorimetric detection(HPLC-FLD).We also examined the morphologies of neurons and synapses in the temporal lobe by transmission electron microscopy(TEM).Our results showed that rats exposed to airport noise of 80 dB had significantly lower line crossing number(P<0.05) and significantly longer center area duration(P<0.05) than control *** 29 d of airport noise exposure,the concentration of plasma NE of exposed rats was significantly higher than that of the control group(P<0.05).We also determined that the neuron and synapsis of the temporal lobe of rats showed signs of damage after aircraft noise of 80 dB exposure for 65 *** conclusion,exposing rats to long-term aircraft noise affects their behaviors,plasma NE levels,and cell morphology of the temporal lobe.

关键词： Aircraft noise Open field test Norepinephrine Neuron Synapse

Microstructural evolution and mechanical properties of aging high nitrogen austenitic stainless steels

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International Journal of Minerals,Metallurgy and Materials 2010年第6期17卷 729-736页

作者： Zhou-hua Jiang Zu-rui Zhang Hua-bing li Zhen li qi-feng Ma School of Materials and Metallurgy Northeastern University Shenyang 110819 China

The microstructural evolution of 18Crl 8Mn2Mo0.77N high nitrogen austenitic stainless steel in aging treatment was investigated by optical microscopy （OM）, scanning electron microscopy （SEM）, and transmission electron microscopy （TEM）. The results show that hexagonal intergranular and cellular Cr2N with a=0.478 nm and c=0.444 nm and body-centered cubic intermetaUic X phase with a=0.892 nm precipitate gradually in the isothermal aging treatment. The matrix nitrogen depletion due to the intergranular Cr2N precipitation induces the decay of Vickers hardness, and the formation of cellular Cr2N and X phase causes the increase in the values. The impact toughness presents a monotonic decrease and SEM morphologies show the leading brittle intergranular fracture. The tensile strength and elongation deteriorate obviously except for the sample aged for 1 h in yield strength. Stress concentration occurs when the matrix dislocations pile up at the pre- cipitation and matrix interfaces, and the interracial dislocations may become precursors to the misfit dislocations, which can form small cleavage steps and accelerate the formation of cracks.

关键词： microstructural evolution aging mechanical properties austenitic stainless steel secondary phase

Curcumin induces apoptosis through the mitochondria-mediated apoptotic pathway in HT-29 cells

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Journal of Zhejiang University-Science B(Biomedicine & Biotechnology) 2009年第2期10卷 93-102页

作者： Jin-bo WANG li-li qi Shui-di ZHENG Tian-xing WU Department of Chemistry College of Science Zhejiang University Hangzhou 310027 China Ningbo Institute of Technology Zhejiang University Ningbo 315100 China

Objective： To investigate the effects of curcumin on release of cytochrome c and expressions of Bcl-2, Bax, Bad, Bcl-xL, caspase-3, poly ADP-ribose polymerase （PARP）, and survivin of HT-29 cells. Methods： HT-29 cells were treated with curcumin （0-80 μmol/L） for 24 h. The release of cytochrome c from the mitochondria and the apoptosis-related proteins Bax, Bcl-2, Bcl-xL, Bad, caspase-3, PARP, and survivin were determined by Western blot analysis and their mRNA expressions by reverse transcriptase-polymerase chain reaction （RT-PCR）. Results： Curcumin significantly induced the growth inhibition and apoptosis of HT-29 cells. A decrease in expressions of Bcl-2, Bcl-xL and survivin was observed after exposure to 10-80 μmol/L curcumin, while the levels of Bax and Bad increased in the curcumin-treated cells. Curcumin also induced the release of cyto- chrome c, the activation ofcaspase-3, and the cleavage of PARP in a dose-dependent manner. Conclusion： These data suggest that curcumin induced the HT-29 cell apoptosis possibly via the mitoehondria-mediated pathway.

关键词： Curcumin Apoptosis Mitochondrial pathway HT-29 cells

Curcumin suppresses PPARδ expression and related genes in HT-29 cells

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World Journal of Gastroenterology 2009年第11期15卷 1346-1352页

作者： Jin-Bo Wang li-li qi Shui-Di Zheng Heng-Zheng Wang Tian-Xing Wu Department of Chemistry College of Science Zhejiang University Hanzhou 310027Zhejiang Province China Ningbo Institute of Technology ZhejiangUniversity Ningbo 315100 Zhejiang Province China

AIM:To investigate the effects of curcumin on the expression of peroxisome proliferator-activated receptorδ(PPARδ)and related genes in HT-29 cells. METHODS:HT-29 cells were treated with curcumin (0-80μmol/L)for 24 *** effects of curcumin on the morphology of HT-29 cells were studied by Hoechst 33342 *** activity of caspase-3 was determined using DEVD-p NA as *** levels of peroxisome PPARδ,14-3-3εand vascular endothelial growth factor(VEGF)in HT-29 cells were determined by Western blotting analysis and their mRNA expression was determined by real-time quantitative RT-PCR. RESULTS:Treatment with 10-80μmol/L curcumin induced typical features of apoptosis and activated the caspase-3 in HT-29 *** expression of PPARδ, 14-3-3εand VEGF was reduced and the activity of β-catenin/Tcf-4 signaling was inhibited by curcumin treatment. CONCLUSION:Curcumin can induce apoptosis of HT-29 cells and down-regulate the expression of PPARδ,14-3-3εand VEGF in HT-29.

关键词： Curcumin 14-3-3ε Peroxisome proliferator-activated receptorδ Vascular endothelial growth factor HT-29 cells

MICROPROPAGATION IN TISSUE CULTURE OFDAHURIAN LARCH

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Journal of Northeast Forestry University 1991年第1期2卷 1-8页

作者： Lu Zhihua li li liu Yuxi qi lizhiNortheast Forestry University Northeast Forestry University China

Dormant buds of Larix gmelinii (4-30 years old) were cultured in vitro. Axillary buds grew on the explants, and 60%-65% of the explants' axillary buds, a differentiation rate of 60% was obtained on the explants collected from the 30-year-old trees. The maximum number of axillary buds was 26 in one induction per initial explant. Bud clusters were separated into individual buds and most of them elongated into shoots. A few roots grew on the shoots. The MS (Murashige and skoog) and SH (Schenk and Hildebrandt) were more efficient media than the WPM. (Woody Plant Medium). The best hormone Combinations for the axillary bud inductions were BA1+NAA0.01 and BA2+NAA0.2 (mg/L). The procedure was as follows: (1) Apical buds were explanted on the no-hormone basal agar medium and grown for 1 or 2 weeks; (2) Explants were transferred onto the bud-inducing medium and grown for 2 weeks and then (3) Cultured on the basal medium without hormones for axillary bud elongation; (4) Bud clusters were separated and cultured continuously to a minimum height of 1.5cm; (5) shoots were cut at the base and cultured on root-inducing medium; (6) plantlets were allowed to acclimatize and then transferred to the soil.

关键词： Larix gmelinii Micropropagatlon Tissue culture

Influence of masticatory fatigue on the fracture resistance of the pulpless teeth restored with quartz-fiber post-core and crown

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International Journal of Oral Science 2012年第4期4卷 218-220页

作者： Er-Min Nie Xia-Yun Chen Chun-Yuan Zhang li-li qi Ying-He Huang Department of Prosthodontics The First Affiliated HospitalSun Yat-Sen University Department of Prosthodontics The Third Affiliated HospitalSun Yat- Sen University Department of Stomatology Taishan People's Hospital

To investigate whether masticatory fatigue affects the fracture resistance and pattern of lower premolars restored with quartz-fiber post-core and full crown, 44 single rooted lower premolars recently extracted from orthodontic patients were divided into two groups of 22 each. The crowns of all teeth were removed and endodontically treated and then restored with quartz-fiber post-core and full crown. Twenty-two teeth in one group were selected randomly and circularly loaded at 45° to the long axis of the teeth of 127.4 N at a 6 Hz frequency, and the other group was not delivered to cyclic loading and considered as control. Subsequently, all teeth in two groups were continually loaded to fail at 45° to the long axis of the teeth at a crosshead speed of 1 ***-1. The mean destructive force values were （733.88±254.99） and （869.14±280.26） N for the experimental and the control group, respectively, and no statistically significant differences were found between two groups （P〉O.05）. Bevel fracture and horizontal fracture in the neck of root were the major fracture mode of the specimens. Under the circumstances of this study, it seems that cyclic loading does not affect the fracture strength and pattern of the quartz-fiber post-core-crown complex.

关键词： fracture resistance masticatory fatigue pulpless teeth quartz-fiber