Showing papers by "Huazhong University of Science and Technology published in 2005"
TL;DR: In this article, the authors review recent progress and advances that have been made on: (a) dispersion of CNTs in a polymer matrix, including optimum blending, in situ polymerization and chemical functionalization; and (b) alignment of CNNs in the matrix enhanced by ex situ techniques, force and magnetic fields, electrospinning and liquid crystalline phase-induced methods.
Abstract: Polymer/carbon nanotube (CNT) composites are expected to have good processability characteristics of the polymer and excellent functional properties of the CNTs. The critical challenge, however, is how to enhance dispersion and alignment of CNTs in the matrix. Here, we review recent progress and advances that have been made on: (a) dispersion of CNTs in a polymer matrix, including optimum blending, in situ polymerization and chemical functionalization; and (b) alignment of CNTs in the matrix enhanced by ex situ techniques, force and magnetic fields, electrospinning and liquid crystalline phase-induced methods. In addition, discussions on mechanical, thermal, electrical, electrochemical, optical and super-hydrophobic properties; and applications of polymer/CNT composites are included. Enhanced dispersion and alignment of CNTs in the polymer matrix will promote and extend the applications and developments of polymer/CNT nanocomposites.
1,848 citations
TL;DR: In this Letter, a new image encryption scheme is presented, in which shuffling the positions and changing the grey values of image pixels are combined to confuse the relationship between the cipher-image and the plain-image.
644 citations
TL;DR: In this article, a well-dispersed silver nanoparticles were prepared by chemical reduction method, with polyvinyl pyrrolidone (PVP) as dispersant, and the mechanisms of PVP in the preparation process were discussed through the optical characters of the reaction system.
571 citations
TL;DR: A mechanism by which HBV-X protein (HBX) upregulates beta-catenin through a docking motif of GSK-3beta is reported, which is supported by immunohistochemical staining in different human tumors, including cancers of the liver, breast, kidney, and stomach.
531 citations
TL;DR: In this article, the authors derived the analytical expressions of the space-time dependent probe field, the corresponding phase shift, absorption or amplification, group velocity, and group velocity dispersion for all three schemes.
Abstract: We analyze the electromagnetically induced transparency (EIT) in $V$-, $\ensuremath{\Lambda}$-, and cascade-type schemes in a time-dependent way via the Schr\"odinger-Maxwell formalism. We derive explicitly the analytical expressions of the space-time dependent probe field, the corresponding phase shift, absorption or amplification, group velocity, and group velocity dispersion for all the three schemes. These simple analytical expressions not only demonstrate explicitly the similarities and essential differences of the three schemes but also provide a convenient basis for investigating how the many-body effects in solids modify the magnitude, spectral shape, and space and time dependence of EIT and EIT-related quantum coherence phenomena.
503 citations
TL;DR: In this article, a solution containing polyvinyl pyrrolidone (PVP), silver nitrate was reduced by the glucose, and silver particles were generated; the possible reaction process is discussed in this paper.
407 citations
TL;DR: Using switched Lyapunov functions, some new general criteria for exponential stability and asymptotic stability with arbitrary and conditioned impulsive switching are established and a new hybrid impulsive and switching control strategy for nonlinear systems is developed.
Abstract: In this note, a new class of hybrid impulsive and switching models is introduced and their asymptotic stability properties are investigated. Using switched Lyapunov functions, some new general criteria for exponential stability and asymptotic stability with arbitrary and conditioned impulsive switching are established. In addition, a new hybrid impulsive and switching control strategy for nonlinear systems is developed. A typical example, the unified chaotic system, is given to illustrate the theoretical results.
401 citations
TL;DR: In this article, an experimental approach on propagation and coalescence of pre-existing cracks (fractures) in marble samples under compression is carried out, and two types of newborn cracks are observed: wing (tensile) cracks and secondary (shear) cracks.
338 citations
31 Oct 2005
TL;DR: This paper proposes to use a hybrid index structure, which integrates inverted files and R*-trees, to handle both textual and location aware queries, and designs and implements a complete location-based web search engine.
Abstract: There is more and more commercial and research interest in location-based web search, i.e. finding web content whose topic is related to a particular place or region. In this type of search, location information should be indexed as well as text information. However, the index of conventional text search engine is set-oriented, while location information is two-dimensional and in Euclidean space. This brings new research problems on how to efficiently represent the location attributes of web pages and how to combine two types of indexes. In this paper, we propose to use a hybrid index structure, which integrates inverted files and R*-trees, to handle both textual and location aware queries. Three different combining schemes are studied: (1) inverted file and R*-tree double index, (2) first inverted file then R*-tree, (3) first R*-tree then inverted file. To validate the performance of proposed index structures, we design and implement a complete location-based web search engine which mainly consists of four parts: (1) an extractor which detects geographical scopes of web pages and represents geographical scopes as multiple MBRs based on geographical coordinates; (2) an indexer which builds hybrid index structures to integrate text and location information; (3) a ranker which ranks results by geographical relevance as well as non-geographical relevance; (4) an interface which is friendly for users to input location-based search queries and to obtain geographical and textual relevant results. Experiments on large real-world web dataset show that both the second and the third structures are superior in query time and the second is slightly better than the third. Additionally, indexes based on R*-trees are proven to be more efficient than indexes based on grid structures.
297 citations
TL;DR: Several criteria for robust local and robust global impulsive synchronization are established for complex dynamical networks, in which the network coupling functions are unknown but bounded.
Abstract: This paper studies robust impulsive synchronization of uncertain dynamical networks. By utilizing the concept of impulsive control and the stability results for impulsive systems, several criteria for robust local and robust global impulsive synchronization are established for complex dynamical networks, in which the network coupling functions are unknown but bounded. Three examples are also worked through for illustrating the main results.
282 citations
TL;DR: A review of the current knowledge and understanding of the photon rest mass, with particular emphasis on a discussion of various experimental methods that have been used to set upper limits on it, can be found in this article.
Abstract: Because classical Maxwellian electromagnetism has been one of the cornerstones of physics during the past century, experimental tests of its foundations are always of considerable interest. Within that context, one of the most important efforts of this type has historically been the search for a rest mass of the photon. The effects of a nonzero photon rest mass can be incorporated into electromagnetism straightforwardly through the Proca equations, which are the simplest relativistic generalization of Maxwell's equations. Using them, it is possible to consider some far-reaching implications of a massive photon, such as variation of the speed of light, deviations in the behaviour of static electromagnetic fields, longitudinal electromagnetic radiation and even questions of gravitational deflection. All of these have been studied carefully using a number of different approaches over the past several decades. This review attempts to assess the status of our current knowledge and understanding of the photon rest mass, with particular emphasis on a discussion of the various experimental methods that have been used to set upper limits on it. All such tests can be most easily categorized in terms of terrestrial and extra-terrestrial approaches, and the review classifies them as such. Up to now, there has been no conclusive evidence of a finite mass for the photon, with the results instead yielding ever more stringent upper bounds on the size of it, thus confirming the related aspects of Maxwellian electromagnetism with concomitant precision. Of course, failure to find a finite photon mass in any one experiment or class of experiments is not proof that it is identically zero and, even as the experimental limits move more closely towards the fundamental bounds of measurement uncertainty, new conceptual approaches to the task continue to appear. The intrinsic importance of the question and the lure of what might be revealed by attaining the next decimal place are as strong a draw on this question as they are in any other aspect of precise tests of physical laws.
TL;DR: Assays in vivo and in vitro against the growth of Sarcoma 180 solid tumor as well as the colorimetric 3-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide method for lentinan showed that the triple-helix sample exhibited a relatively high inhibition ratio.
TL;DR: A delay-dependent sufficient condition is derived in terms of linear matrix inequalities (LMIs) by using a descriptor model transformation of the system and by applying Moon's inequality for bounding cross terms.
TL;DR: The results strongly suggest that CYP epoxygenase 2J2 plays a previously unknown role in promotion of the neoplastic cellular phenotype and in the pathogenesis of a variety of human cancers.
Abstract: Cytochrome P450 (CYP) arachidonic acid epoxygenase 2J2 converts arachidonic acid to four regioisomeric epoxyeicosatrienoic acids, which exert diverse biological activities in cardiovascular system and endothelial cells. However, it is unknown whether this enzyme highly expresses and plays any role in cancer. In this study, we found that very strong and selective CYP2J2 expression was detected in human carcinoma tissues in 101 of 130 patients (77%) as well as eight human carcinoma cell lines but undetectable in adjacent normal tissues and nontumoric human cell lines by Western, reverse transcription-PCR, and immunohistochemical staining. In addition, forced overexpression of CYP2J2, and CYP BM3F87V or addition of epoxyeicosatrienoic acids (EET) in cultured carcinoma cell lines in vitro markedly accelerated proliferation by analyses of 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide, cell accounts, and cell cycle analysis, and protected carcinoma cells from apoptosis induced by tumor necrosis factor alpha (TNF-alpha) in cultures. In contrast, antisense 2J2 transfection or addition of epoxygenase inhibitors 17-ODYA inhibited proliferation and accelerated cell apoptosis induced by TNF-alpha. Examination of signaling pathways on the effects of CYP2J2 and EETs revealed activation of mitogen-activated protein kinases and PI3 kinase-AKT systems and elevation of epithelial growth factor receptor phosphorylation level. These results strongly suggest that CYP epoxygenase 2J2 plays a previously unknown role in promotion of the neoplastic cellular phenotype and in the pathogenesis of a variety of human cancers.
TL;DR: A novel real-time route planner for unmanned air vehicles that incorporates domain-specific knowledge, can handle unforeseeable changes of the environment, and take into account different kinds of mission constraints such as minimum route leg length and flying altitude.
Abstract: Based on evolutionary computation, a novel real-time route planner for unmanned air vehicles is presented. In the evolutionary route planner, the individual candidates are evaluated with respect to the workspace so that the computation of the configuration space is not required. The planner incorporates domain-specific knowledge, can handle unforeseeable changes of the environment, and take into account different kinds of mission constraints such as minimum route leg length and flying altitude, maximum turning angle, and fixed approach vector to goal position. Furthermore, the novel planner can be used to plan routes both for a single vehicle and for multiple ones. With Digital Terrain Elevation Data, the resultant routes can increase the surviving probability of the vehicles using the terrain masking effect.
TL;DR: The data suggest that podocyturia may become a more sensitive means to assess the activity of glomerular damage than proteinuria, and not simply a reflection of proteinuria because it is limited to phases of ongoingglomerular injury.
Abstract: Podocyte loss contributes to the development of glomerulosclerosis. Although podocyte detachment has been recognized as a new mechanism of podocyte loss in glomerular diseases, its time course and relationship to disease activity are not known. Urinary excretion of viable podocytes was quantified in two models of transient glomerular injury, i.e., rats with puromycin aminonucleoside-induced nephrosis (PAN) and mesangioproliferative nephropathy (anti-Thy 1.1 nephritis model), as well as in a model of continuous glomerular injury, i.e., hypertensive nephropathy (5/6-nephrectomy model), and in aging rats. The number of glomerular Wilm's tumor (WT)-1-positive podocytes and the glomerular expression of cell-cycle proteins in vivo were assessed. Urinary podocyte loss occurred in both primary (PAN) and secondary (anti-Thy 1.1 nephritis) in parallel to the onset of proteinuria. However, subsequently proteinuria persisted despite remission of podocyturia. In continuous glomerular injury, i.e., after 5/6-nephrectomy, podocyturia paralleled the course of proteinuria and of systemic hypertension, whereas no podocyturia became detectable during normal aging (up to 12 mo). Despite podocyte detachment of varying degrees, no decrease in glomerular podocyte counts (i.e., WT-1 positive nuclei) was noted in either disease model. Podocyturia in the PAN and anti-Thy 1.1 nephritis model was preceded by entry of glomerular podocytes into the cell cycle, i.e., cyclin D1, cdc2, and/or proliferating cell nuclear antigen (PCNA) expression. Podocyturia is a widespread phenomenon in glomerular disease and not simply a reflection of proteinuria because it is limited to phases of ongoing glomerular injury. The data suggest that podocyturia may become a more sensitive means to assess the activity of glomerular damage than proteinuria.
TL;DR: It is shown that IKK is activated in a mouse model of stroke, indicating a key function of IKK in ischemic brain damage and suggesting a potential role for IKK inhibitors in stroke therapy.
Abstract: The IkappaB kinase complex IKK is a central component of the signaling cascade that controls NF-kappaB-dependent gene transcription. So far, its function in the brain is largely unknown. Here, we show that IKK is activated in a mouse model of stroke. To investigate the function of IKK in brain ischemia we generated mice that contain a targeted deletion of Ikbkb (which encodes IKK2) in mouse neurons and mice that express a dominant inhibitor of IKK in neurons. In both lines, inhibition of IKK activity markedly reduced infarct size. In contrast, constitutive activation of IKK2 enlarged the infarct size. A selective small-molecule inhibitor of IKK mimicked the effect of genetic IKK inhibition in neurons, reducing the infarct volume and cell death in a therapeutic time window of 4.5 h. These data indicate a key function of IKK in ischemic brain damage and suggest a potential role for IKK inhibitors in stroke therapy.
TL;DR: Near-infrared fluorescence optical imaging is a powerful technique for studying diseases at the molecular level in preclinical models and recently reported that monomeric RGD peptide c(RGDyK) conju...
TL;DR: In this article, a lifetime-broadened four-state, ladder-type four-wave mixing (FWM) scheme was proposed for optical soliton formation and a pair of matched solitons with the same temporal shape and ultraslow group velocity was obtained.
Abstract: We analyze a lifetime-broadened four-state, ladder-type four-wave mixing (FWM) scheme in the context of optical soliton formation. We show that a pulsed probe field and a pulsed FWM field of considerably different frequency can evolve into a pair of matched solitons with the same temporal shape and ultraslow group velocity $({V}_{g}∕c\ensuremath{\sim}{10}^{\ensuremath{-}3})$, i.e., two-color ultraslow optical solitons. In addition, we show regimes where two-color superluminal $({V}_{g}∕cl0)$ optical soliton propagation may occur.
TL;DR: The data show that NF-κB is activated in neurons and astrocytes during cerebral ischemia and that NF -κB activation in neurons contributes to the ischemic damage.
Abstract: The transcription factor NF-kappaB is a key regulator of inflammation and cell survival. NF-kappaB is activated by cerebral ischemia in neurons and glia, but its function is controversial. To inhibit NF-kappaB selectively in neurons and glial cells, we have generated transgenic mice that express the IkappaBalpha superrepressor (IkappaBalpha mutated at serine-32 and serine-36, IkappaBalpha-SR) under transcriptional control of the neuron-specific enolase (NSE) and the glial fibrillary acidic protein (GFAP) promoter, respectively. In primary cortical neurons of NSE-IkappaBalpha-SR mice, NF-kappaB activity was partially inhibited. To assess NF-kappaB activity in vivo after permanent middle cerebral artery occlusion (MCAO), we measured the expression of NF-kappaB target genes by real-time polymerase chain reaction (PCR). The induction of c-myc and transforming growth factor-beta2 by cerebral ischemia was inhibited by neuronal expression of IkappaBalpha-SR, whereas induction of GFAP by MCAO was reduced by astrocytic expression of IkappaBalpha-SR. Neuronal, but not astrocytic, expression of the NF-kappaB inhibitor reduced both infarct size and cell death 48 hours after permanent MCAO. In summary, the data show that NF-kappaB is activated in neurons and astrocytes during cerebral ischemia and that NF-kappaB activation in neurons contributes to the ischemic damage.
TL;DR: It is concluded that AA epoxygenase metabolites can promote angiogenesis, which may provide protection to ischemic tissues and the angiogenic effects of EETs involve the MAPK and PI3-kinase/Akt signaling pathways, and to some extent, the eNOS pathway.
Abstract: Cytochrome P450 arachidonic acid (AA) epoxygenase metabolites, the epoxyeicosatrienoic acids (EETs), dilate arteries via hyperpolarization of smooth muscle cells and also have nonvasodilatory effects within the vasculature. The present study investigated the angiogenic effects of endogenous and exogenous EETs and the relevant signaling mechanisms involved. Bovine aortic endothelial cells (BAECs) were incubated with synthetic EETs or infected with recombinant adeno-associated viruses (rAAVs) containing CYP2C11-NADPH-cytochrome P450 oxidoreductase (CYPOR), CYP2J2, or CYP102 F87V mutant to increase endogenous levels of EETs. The following endpoints were measured: BAEC proliferation, migration, capillary formation, and in vivo angiogenesis. The potential involvement of various signaling pathways was explored using selective inhibitors. The results showed that transfection with either rAAV-CYP2C11-CYPOR, rAAV-CYP2J2, or rAAV-CYP102 F87V, or incubation with EETs promoted BAEC proliferation, increased migration of BAECs as assessed by Transwell analysis and wound healing assays, and enhanced capillary tubule formation as determined by chicken embryo chorioallantoic membrane assays and tube formation tests on matrigel. The effects of EETs on proliferation, migration, and capillary tubule formation were attenuated by inhibitors of mitogen-activated protein kinase (MAPK) and phosphatidylinositol 3 (PI3)-kinase/Akt pathways and partially attenuated by an endothelial nitric-oxide synthase (eNOS) inhibitor but not by a protein kinase C inhibitor. In a rat ischemic hind limb model, rAAV-mediated AA epoxygenase transfection induced angiogenesis. We conclude that AA epoxygenase metabolites can promote angiogenesis, which may provide protection to ischemic tissues. The results also suggest that the angiogenic effects of EETs involve the MAPK and PI3-kinase/Akt signaling pathways, and to some extent, the eNOS pathway.
01 Jan 2005
TL;DR: In this paper, the 3D temperature distributions of combustion in the pulverized-coal-fired boiler furnace of a 200MW power generation unit were visualized experimentally using a novel flame image processing technique.
Abstract: By using a novel flame image processing technique, the 3-D temperature distributions of combustion in the pulverized-coal-fired boiler furnace of a 200 MW power generation unit were visualized experimentally With the assumption of gray radiation, multiple color flame image detectors were used to capture approximately monochromatic radiation intensity images under the visible wavelengths of red (R), green (G), and blue (B), and a blackbody furnace was used to calibrate the color images A way to calculate the radiation intensity using the Monte Carlo method was used to establish the relationship between the radiation flame images and the 3-D temperature distribution inside the furnace, given the radiative parameters such as the absorption and scattering coefficients of the combustion medium A modified Tikhonov regularization method was used to reconstruct the 3-D temperature distribution from the 2-D flame temperature images transformed from the color flame images Eight flame image detectors were mounted close to the four corners in four layers in different heights in the furnace, the 3-D temperature distribution in 1200 discrete meshes in 12 layers along the height of the furnace was reconstructed from the eight flame images, and the visualization result was updated within 5 s The errors between some local temperatures visualized by the present system with those measured by a suction thermocouple were within ±5%, showing applicability of the method On-line monitoring results demonstrated that the average temperature inside the furnace changed directly proportionally with the load of the unit The preliminary results show that this technology will be useful for the combustion diagnosis and control in coal-fired power generation plants
TL;DR: In this article, the electronic structure and the ferromagnetism of CrS and UP in the zinc-blende (ZB) phase are investigated by spin-polarized calculations with first-principles plane-wave pseudopotential method within the generalized gradient approximation for the exchange-correlation potential.
TL;DR: In this paper, an analytical model for fractal dimension of tortuous streamtubes in porous media is derived, and the proposed fractal dimensions are expressed as a function of porosity and scale.
Abstract: An analytical model for fractal dimension of tortuous streamtubes in porous media is derived. The proposed fractal dimension for tortuous streamtubes in porous media is expressed as a function of porosity and scale, and there is no empirical constant in the proposed expression. The model predictions for the fractal dimension of tortuous streamtubes in porous media are in good agreement with those by the box-counting method and with the observations of other researchers.
TL;DR: Hoechst 33258 staining showed that curcumin could induce Raji cell apoptosis, andCurcumin, as a new member of the histone deacetylase inhibitors, can inhibit the expression of class I HDACs (HDAC1, HDAC3, and HDAC8), and can increase theexpression of Ac-histone H4 in Raji cells.
Abstract: To investigate curcumin (diferuloylmethane) induced apoptosis and its molecular mechanism of action in B-NHL cell line Raji cells. Raji cells were cultured in RPMI-1640 medium and treated with curcumin in different concentrations. 3-(4,5-Dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium (MTT) assay was used to detect growth inhibition and Hoechst 33258 staining was used to detect apoptosis. Immunocytochemistry and Western blot were used to detect the expressions of histone deacetylase 1, 3, and 8 (HDAC1, HDAC3, and HDAC8) and acetylated histone H4 (Ac-histone H4) protein. Curcumin inhibited the proliferation of B-NHL cell line Raji cells with a 36-h IC50 value of 24.1±2.0 μmol/L. Hoechst 33258 staining showed that curcumin could induce Raji cell apoptosis. The expression levels of HDAC1, HDAC3, and HDAC8 proteins were downregulated following curcumin treatment in Raji cells, whereas Ac-histone H4 protein expression was upregulated after treatment with curcumin. Curcumin, as a new member of the histone deacetylase inhibitors, can inhibit the expression of class I HDACs (HDAC1, HDAC3, and HDAC8), and can increase the expression of Ac-histone H4 in Raji cells. Curcumin plays an important role in regulating B-NHL cell line Raji cell proliferation and apoptosis.
TL;DR: In this article, an ant colony algorithm-based approach to assembly sequence generation and optimization of mechanical products is presented, where different amount of ants cooperate to find optimal solutions with the least reorientations during assembly processes.
Abstract: An ant colony algorithm-based approach to assembly sequence generation and optimization of mechanical products is presented in this article. For diverse assemblies, the approach generates different amount of ants cooperating to find optimal solutions with the least reorientations during assembly processes. Based on assembly by disassembly philosophy, a candidate list composed by feasible and reasonable disassembly operations that are derived from disassembly matrix guides sequences construction in the solution space expressed implicitly, and so guarantees the geometric feasibility of sequences. The state-transition rule and local- and global-updating rules are defined to ensure acquiring of the optimal solutions. Cases are given to show the effectiveness of the proposed approach, and the characteristics of the algorithm are discussed.
TL;DR: A review of the state-of-the-art in this field can be found in this article, highlighting the key areas of development, including the modelling of the soil media and various analytical as well as numerical approaches in analysing the interaction action between the foundation and soil.
Abstract: The interaction action between structures and supporting soil media is of fundamental importance in foundation design and it has always attracted the attention of both researchers and engineers. This paper reviews the state-of-the-art in this field, highlighting the key areas of development, including the modelling of the soil media and various analytical as well as numerical approaches in analysing the interaction action between the foundation and soil. Copyright © 2005 John Wiley & Sons, Ltd.
TL;DR: Direct electrochemistry of hemoglobin (Hb) is observed at carbon nanotube (CNT) interface and it is found that the adsorbing Hb still keeps its catalytic activity to H(2)O(2).
TL;DR: In this article, the effects of three parameters, elevation, aspect ratio, and side ratio, on bluff-body flow and thereby on the local wind forces are discussed, and the overall loads and base moments are obtained by integration of local wind force coefficients.
TL;DR: This paper provides a number of illustrations of how Chinese e-government initiatives can be best understood as vehicles intended to support economic development through an increasingly transparent and decentralized administration while at the same time providing the central government the information and ability to efficiently monitor and potentially steer economic activity at a more abstract level.