Showing papers by "China Three Gorges University published in 2010"

An Unprecedented Eight-Connected Self-Penetrating Coordination Framework Based on Cage-Shaped [Pb6(μ4-O)2(O2C)8] Clusters

Abstract: A unique self-penetrating coordination framework with (424.64) network topology is constructed from cage-shaped [Pb6(μ4-O)2(O2C)8] clusters as eight-connected nodes and long V-shaped dicarboxylate backbones as spacers, which interestingly can be regarded as the cross-linking of two interpenetrating six-connected pcu networks.

Influence of the impounding process of the Three Gorges Reservoir up to water level 172.5 m on water eutrophication in the Xiangxi Bay

Abstract: The water level of the Three Gorges Reservoir (TGR) rose to 172.5 m in two stages from September to November, 2008. The hydrodynamic parameters and water quality parameters (e.g. flow velocity, temperature, turbidity and nutrient content) had been continuously monitored to reveal the influence of the impounding process of the TGR on the water eutrophication in the Xiangxi Bay (XXB). The maximal daily rise of the water level of the TGR was about 2.38 m. The water exchange between the mainstream (the Changjiang River) and the XXB of the TGR was enhanced by density current, and its main characteristics were a density-stratified flow in different directions. The water exchange reduced the differences of the water quality parameters (for example, temperature, turbidity, nutrient level, pH, etc.) between the mainstream and the XXB during the impounding process. Meanwhile, the water stability index in the mainstream remained small but it was lowered in the XXB. The main causes included the dilution by water of lower concentration of the chlorophyll a (Chl. a) entering from the mainstream, the decline of the water stability, and the increase of suspended silt, which induced the Chl.a to decrease in the XXB during the impounding process. The grade of the water eutrophication changed from middle eutrophic level to mesotrophic state in the process. However, as available nutrients were imported into the XXB from the mainstream during the impounding process the risk of water eutrophication increases in the XXB in the future.

Rapamycin regulates Akt and ERK phosphorylation through mTORC1 and mTORC2 signaling pathways

Abstract: Numerous studies have shown that mammalian target of rapamycin (mTOR) inhibitor activates Akt signaling pathway via a negative feedback loop while inhibiting mTORC1 signaling. In this report, we focused on studying the role of mTORC1 and mTORC2 in rapamycin-mediated Akt and ERK phosphorylation, and the antitumor effect of rapamycin in cancer cells in combination with Akt and ERK inhibitors. Moreover, we analyzed the effect of mTORC1 and mTORC2 on regulating cell cycle progression. We found that low concentrations rapamycin increased Akt and ERK phosphorylation through a mTORC1-dependent mechanism because knockdowned raptor induced the activation of Akt and ERK, but higher doses of rapamycin inhibited Akt and ERK phosphorylation mainly via the mTORC2 signaling pathway because that the silencing of rictor led to the inhibition of Akt and ERK phosphorylation. We further showed that mTORC2 was tightly associated with the development of cell cycle through an Akt-dependent mechanism. Therefore, we combined PI3K and ERK inhibitors prevent rapamycin-induced Akt activation and enhanced antitumor effects of rapamycin. Collectively, we conclude that mTORC2 plays a much more important role than mTORC1 in rapamycin-mediated phosphorylation of Akt and ERK, and cotargeting AKT and ERK signaling may be a new strategy for enhancing the efficacy of rapamycin-based therapeutic approaches in cancer cells.

Unique 3D self-penetrating CoII and NiII coordination frameworks with a new (44.610.8) network topology

Abstract: Two unique six-connected self-penetrating coordination polymers with a new (44.610.8) network topology, derived from the cross-linking of two 66-dia subnets, were constructed from NiII or CoII and two types of V-shaped tectons. The NiII complex 1 shows an antiferromagnetic coupling via μ-carboxylate and μ-H2O pathways, whereas the CoII complex 2 exhibits the single-ion behavior in 300–34 K and then a ferromagnetic coupling at lower temperatures.

Multi-objective Cultured Differential Evolution for Generating Optimal Trade-offs in Reservoir Flood Control Operation

Abstract: Reservoir flood control operation (RFCO) is a complex problem because it needs to consider multiple objectives and a large number of constraints. Traditional methods usually convert multiple objectives into a single objective to solve, using weighted methods or constrained methods. In this paper, a new approach named multi-objective cultured differential evolution (MOCDE) is proposed to deal with RFCO. MOCDE takes cultural algorithm as its framework and adopts differential evolution (DE) in its population space. Considering the features of DE and multi-objective optimization, three knowledge structures are defined in belief space to improve the searching efficiency of MOCDE. MOCDE is first tested on several benchmark problems and compared with some well known multi-objective optimization algorithms. On achieving satisfactory performance for test problems, MOCDE is applied to a case study of RFCO. It is found that MOCDE provides decision makers many alternative non-dominated schemes with uniform coverage and convergence to true Pareto optimal solutions in a short time. The results obtained show that MOCDE can be a viable alternative for generating optimal trade-offs in reservoir multi-objective flood control operation.

Statins attenuate high mobility group box-1 protein induced vascular endothelial activation : a key role for TLR4/NF-κB signaling pathway

Abstract: High mobility group box-1 (HMGB1) has recently been implicated as a proinflammatory cytokine that plays critical roles in endothelial dysfunction and atherosclerosis Atorvastatin, a 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitor, exerts anti-inflammatory effects in the cardiovascular system beyond its cholesterol-lowering property The aim of our study was to investigate whether atorvastatin inhibits HMGB1-induced vascular endothelial activation, and elucidate the underlying molecular mechanism In this study, we found that atorvastatin, at concentrations ranging from 01 to 10 μM, effectively and in a dose-dependent manner inhibited HMGB1-induced endothelial cells (ECs) activation Incubation of ECs with 10 μM atorvastatin reduced adhesion molecules (ICAM-1 and E-selectin) expression concomitant with a significant inhibition in HMGB1-stimulated leukocyte-endothelial adhesion Further experiments showed that atorvastatin markedly suppressed HMGB1-induced Toll like receptor 4 (TLR4) expression, Nuclear factor kappaB (NF-κB) nuclear translocation and DNA binding activity in ECs Similar effects were also observed in ECs pretreated with the TLR4- specific inhibitor CLI-095, suggesting an important role of TLR4/NF-κB pathway These findings indicate that atorvastatin attenuates HMGB1-induced vascular endothelial activation The underlying mechanism involves, at least in part, inhibition of TLR4/NF-κB-dependent signaling pathway, which provied the new evidence for therapeutic application of statins to target inflammatory processes in cardiovascular disease

Loading of VEGF to the heparin cross-linked demineralized bone matrix improves vascularization of the scaffold.

Abstract: Deficient vascularization is one of the prominent shortcomings of porous tissue-engineering scaffolds, which results in insufficient oxygen and nutrients transportation. Here, heparin cross-linked demineralized bone matrices (HC-DBM) pre-loaded with vascular endothelial growth factor (VEGF) were designed to promote cells and new microvessels invasion into the matrices. After being chemical crosslinked with heparin by N-hydroxysuccinimide and N-(3-di-methylaminopropyl)-N’-ethylcarbodiimide, the scaffold could bind more VEGF than the non-crosslinked one and achieve localized and sustained delivery. The biological activity of VEGF binding on heparinized collagen was demonstrated by promoting endothelial cells proliferation. Evaluation of the angiogenic potential of heparinized DBM loaded with VEGF was further investigated by subcutaneous implantation. Improved angiogenesis of heparinized DBM loaded with VEGF was observed from haematoxylin-eosin staining and immunohistochemistry examination. The results demonstrated that heparin cross-linked DBM binding VEGF could be a useful strategy to stimulate cells and blood vessels invasion into the scaffolds.

A versatile V-shaped tetracarboxylate building block for constructing mixed-ligand Co(II) and Mn(II) complexes incorporating various N-donor co-ligands

Abstract: Hydrothermal reactions of 3,3′,4,4′-diphenylsulfonetetracarboxylic dianhydride with Co(II) or Mn(II) acetate and systematically varied N-donor co-ligands leads to the formation of a series of supramolecular complexes, namely, [Co(H2dpstc)(trpy)·H2O] (1), [Co2(dpstc)(phen)2·4H2O]·2H2O (2), [Mn2(dpstc) (phen)2·5H2O] (3), [Mn2(dpstc)(bipy)2·3H2O]·H2O (4) and [Mn2(dpstc)(bpe)2·2H2O]·2H2O (5), where dpstc = 3,3′,4,4′-diphenylsulfonetetracarboxylate, trpy = 2,2′:6′,2′′-terpyridine, phen = 1,10-phenthro- line, bipy = 2,2′-bipyridine and bpe = 1,2-di(4-pyridyl)ethylene. Single-crystal X-ray analysis reveals that complex 1 shows a simple 1D linear array, 2 exhibits a unique 1D chain with pendant arms, and 3 displays a binuclear core. Interestingly, such 1D or dimeric coordination motifs in 1–3 hold the recognition sites of hydrogen bonding and/or π–π stacking, which result in the extended 3D architectures. In contrast, complexes 4 and 5 represent a 2D (4,4) layer and a 3D 4-connected (64·82) framework, respectively. By careful inspection of the structures for 1–5, it is clear that the tetracarboxylate with different coordination modes as well as the auxiliary N-donor ligands play a critical role in determining the coordination array and further packing modes of the final 3D lattice architectures. Magnetic susceptibilities of complexes 1–5 reveals the weak antiferromagnetic exchange interactions between the adjacent metal centers and their thermal stability has also been studied.

Preparation of reactive powder concrete using fly ash and steel slag powder

Abstract: To decrease the cement and SF content of RPC by using ultra-fine fly ash (UFFA) and steel slag powder (SS), the effect of these mineral admixtures on compressive strength of RPC were investigated. The experimental results indicate that the utilization of UFFA and SS in RPC is feasible and has prominent mechanical performance. The microstructure analysis (SEM and TG-DTG-DSC) demonstrated that the excellent mechanical properties of RPC containing SS and UFFA were mainly attributed to the sequential hydration filling effect of the compound system.

Influence of dynamic load on friction behavior of human articular cartilage, stainless steel and polyvinyl alcohol hydrogel as artificial cartilage.

Abstract: Many biomaterials are being developed to be used for cartilage substitution and hemiarthroplasty implants. The lubrication property is a key feature of the artificial cartilage. The frictional behavior of human articular cartilage, stainless steel and polyvinyl alcohol (PVA) hydrogel were investigated under cartilage-on-PVA hydrogel contact, cartilage-on-cartilage contact and cartilage-on-stainless steel contact using pin-on-plate method. Tests under static load, cyclic load and 1 min load change were used to evaluate friction variations in reciprocating motion. The results showed that the lubrication property of cartilage-on-PVA hydrogel contact and cartilage-on-stainless steel contact were restored in both 1 min load change and cyclic load tests. The friction coefficient of PVA hydrogel decreased from 0.178 to 0.076 in 60 min, which was almost one-third of the value under static load in continuous sliding tests. In each test, the friction coefficient of cartilage-on-cartilage contact maintained far lower value than other contacts. It is indicated that a key feature of artificial cartilage is the biphasic lubrication properties.

Estrogenic and Antiestrogenic Activities of Phloridzin

Abstract: Phloridzin, a phloretin 2'-beta-D-glucoside, belongs to dihydrochalcones and mainly exists in the fruits of Malus pumila Mill., Lithocarpus polystachyus REHD and the root skins, stems, tender leaves and fruits of Malus hupehensis. It has many pharmacological activities, such as regulating blood sugar level and blood pressure, protecting heart, scavenging of oxygen free radicals and antioxidant injuries. Thus, market demand of products containing phloridzin is increasing year by year. Our research results demonstrated that phloridzin is provided with a double directional adjusting function of estrogenic and antiestrogenic activities. It showed significant effects on the proliferation of estrogen sensitive estrogen receptor (ER) (+)MCF-7 cells in the absence of estrogen. When added with 17beta-estradiol, phloridzin showed antagonism on estradiol-induced MCF-7 cell proliferation, but it did not significantly affect proliferation of estrogen insensitive ER (-)MDA-MB-231 cells. Phloridzin induced beta-galactosidase activity in a yeast two-hybrid assay. Light increase of the uterine weight and serum estradiol content of mouse was observed when the glucoside was administered orally for 7 d. After oral administration, phloridzin was found mainly in the blood and a small part was metabolized to phloretin. Our investigation proved that phloridzin was distributed at the target organ and played the role of phytoestrogen.

Aligned gold nanoneedle arrays for surface-enhanced Raman scattering.

Abstract: A simple Ar(+)-ion irradiation route has been developed to prepare gold nanoneedle arrays on glass substrates for surface-enhanced Raman scattering (SERS)-active substrates. The nanoneedles exhibited very sharp tips with an apex diameter of 20 nm. These arrays were evaluated as potential SERS substrates using malachite green molecules and exhibited a SERS enhancement factor of greater than 10(8), which is attributed to the localized electron field enhancement around the apex of the needle and the surface plasmon coupling originating from the periodic structure. This work demonstrates a new technique for producing controllable and reproducible SERS substrates potentially applicable for chemical and biological assays.

The comparative study on the ecological sensitivity analysis in Huixian karst wetland, China

Abstract: This paper applies two methods to analyze the ecological sensitivity in Huixian wetland, (Guangxi province, China). The one method (the ecological unit method) is that the Huixian wetland reserve is divided into several ecological units according to different geographic condition and agricultural structure; the main factors of ecological sensitivity are selected; Delphi and Analytical Hierarchy Process (AHP) are applied to determine evaluation factors and the weight of each factor; at last, Index Accumulation Method (IAM) is adopted to evaluate the ecological sensitivity. The other method (the GIS method) is that using ecological sensitivity indexes and GIS spatial analysis module, makes a comprehensive evaluation of the ecological sensitivity in Huixian wetland. The results of the ecological sensitivity analysis show that the most sensible zone lies in the centre of the wetland reserve, which can be set to the core protection area. The high sensibility zone is around the core protection area, which can be set to the buffer zone or experimental zone. The lowest sensibility zone is located in the east of the wetland reserve, which can be set to the demonstration area. The compared results of the two different methods show that the first method, the ecological unit method, can be used in case of comparative shortage of existing data. The ecological sensibility distribution is relatively explicit. The second method, the GIS method, can be used in case of the abundant Remote Sensing (RS) and geographic information systems (GIS) data. The analytical results are meticulous and objective. The ecological sensibility distribution is relatively implicit.

Dynamic features and effects of rainfall on landslides in the Three Gorges Reservoir region, China: using the Xintan landslide and the large Huangya landslide as the examples

Abstract: The study area is located in Three Gorges Reservoir region, China. Over 200 landslides have been monitored over a number of years with their behavior being compared to the effective rainfall database for the study area. Analysis of the available data indicates that the occurrences of landslides in this region are controlled by rainfall, whose intensity and rainfall processes are the most important dynamic factors in determining the stability of slopes. Therefore, the relationship between rainfall and the movement of typical landslides has been specifically analyzed for the Xintan landslides and the large Huangya landslide by using the loading/unloading response ratio parameter of rainfall. The result of this study indicates that the mutation of the loading/unloading response ratio of rainfall of the Xintan landslide and the large Huangya landslide in the Three Gorges Reservoir region, China occurred just before their destabilization, which shows that the loading/unloading response ratio of rainfall and its changing feature can be taken as a precursor for the landslides induced by rainfall.

Effects of Reservoir Impounding on Key Ecological Factors in the Three Gorges Region

Abstract: According to the analyzing of the monitoring data of key ecological factors, such as concentration of total phosphorus (TP), concentration of total nitrogen (TN), and algae cell density during 2002-2005 in the reservoir region, we can find that the number of algae species and the cell density are significant increase, nutrient concentration in Xiangxi Bay also has marked increasing tendency after impounding. It creates a necessary condition for the outbreaking of algal blooms in the tributary bay. Hydraulic structures locates in the tributaries upstream are suggested to be used to regulate and control water quality in the bays.

Effect of Mn content on the microstructure and mechanical properties of Mo2FeB2 based cermets

Abstract: Five series of Mo2FeB2 based cermets with Mn addition between 0 and 10 wt% in 2.5 wt% increments were prepared by reaction sintering process. The effect of Mn content on the microstructure and crystalline phases was investigated by transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX) and X-ray diffraction (XRD). Hardness (HRA) and transverse rupture strength (TRS) were also measured. Mn addition improved the wettability of the Fe binder phase on the Mo2FeB2 hard phase, which resulted in a decrease in porosity and Mo2FeB2 grain size and an increase in phase uniformity. No Fe–Mn intermetallic compounds or other intermetallic compounds were detected with increasing Mn content. The TRS increased with increasing Mn content until it reached the maximum value at 10.0 wt% Mn addition. The hardness slightly increased with increasing Mn content firstly and then turned to decrease with increasing Mn content. The highest hardness was obtained for cermets with 5.0 wt% Mn addition.

Exponential stability and exponential stabilization of singularly perturbed stochastic systems with time‐varying delay

Abstract: In this paper, the problems of exponential stability and exponential stabilization for linear singularly perturbed stochastic systems with time-varying delay are investigated. First, an appropriate Lyapunov functional is introduced to establish an improved delay-dependent stability criterion. By applying free-weighting matrix technique and by equivalently eliminating time-varying delay through the idea of convex combination, a less conservative sufficient condition for exponential stability in mean square is obtained in terms of e-dependent linear matrix inequalities (LMIs). It is shown that if this set of LMIs for e=0 are feasible then the system is exponentially stable in mean square for sufficiently small e⩾0. Furthermore, it is shown that if a certain matrix variable in this set of LMIs is chosen to be a special form and the resulting LMIs are feasible for e=0, then the system is e-uniformly exponentially stable for all sufficiently small e⩾0. Based on the stability criteria, an e-independent state-feedback controller that stabilizes the system for sufficiently small e⩾0 is derived. Finally, numerical examples are presented, which show our results are effective and useful. Copyright © 2010 John Wiley & Sons, Ltd.

High mobility group box-1 and cardiovascular diseases.

Abstract: High mobility group box-1 (HMGB1) is a highly conserved, ubiquitous protein in the nuclei and cytoplasm of almost all cells. After binding to its receptor, HMGB1, which is derived from necrotic cells and activated macrophages/monocytes, functions as a critical mediator of inflammation and promotes tissue repair and regeneration. Many recent studies demonstrated that HMGB1 played a pivotal role in cardiovascular diseases, such as atherosclerosis, myocardial ischemia/reperfusion injury, heart failure, and myocardial infarction. In this review, we focus on HMGB1 and summarize the association of HMGB1 with cardiovascular diseases.

A new naphtho-γ-pyrone from mangrove endophytic fungus ZSU-H26

Abstract: A new naphtho-γ-pyrone, 5-hydroxy-6,8-dimethoxy-2-benzyl-4H-naphtho[2,3-b]-pyran-4-one (1), together with three known compounds 5,7-dihydroxy-2-methylbenzopyran-4-one (2), 3,5-dihydroxy-2,7dimethylbenzopyran-4-one (3) and cyclo(Tyr-Tyr) (4) were isolated from the mangrove endophytic fungus Phomopsis sp. ZSU-H26 obtained from the South China Sea. Their structures were elucidated by spectroscopic methods, mainly 1D and 2D NMR spectroscopic techniques. Primary bioassays showed that 1 exhibited cytotoxicity against HEp-2 and HepG2 cells with IC50 values of 10 and 8 μg/mL, respectively.