Showing papers by "Sichuan University published in 1999"
TL;DR: TGF-beta1 is a key mediator that regulates, in a dose-dependent fashion, transdifferentiation of tubular epithelial cells into alpha-SMA+ myofibroblasts, which is markedly enhanced by growth on collagen type I.
490 citations
TL;DR: In this article, a flattened Brazilian disk specimen subjected to compression is proposed for testing fracture toughness KIC of quasi-brittle materials such as rocks, the important condition for crack initiation at the center of the disk during testing is outlined, which is closely linked to the load angle determined by the width of the flatten.
146 citations
TL;DR: In this article, a detailed study of the propagation properties of cosh-Gaussian (ChG) beams has been made, where the passage of ChG beams through a first-order paraxial optical ABCD system has been expressed in closed forms for both unapertured and apertured cases.
126 citations
TL;DR: Modulation measurement profilometry has the advantage of measuring the surface of a test object by perpendicular projection, that is, the direction of the CCD camera is the same as that of the projecting light, and the wrapped phases need not be calculated.
Abstract: We present a detailed discussion of how modulation measurement profilometry (MMP) is applied to measuring an object that has holes on its surface. MMP is not based on the conventional three-dimensional profilometry method with structured light triangulation but on modulation measurements; it has the advantage of measuring the surface of a test object by perpendicular projection, that is, the direction of the CCD camera is the same as that of the projecting light, and the wrapped phases need not be calculated. Thus the difficulties from shadows and spatial discontinuities in phase measurement profilometry and Fourier transform profilometry methods do not exist in MMP. Here we measure a wheellike object that is 31.5 mm thick with an outer diameter of 80 mm and an inner diameter of 20 mm. All the object seen with the CCD camera can be measured including the hole. Experimental results prove that this method is useful for three-dimensional profilometry measurement, especially for objects with discontinuous height steps and spatial isolation.
96 citations
TL;DR: The results of inductively coupled plasma spectra, scanning electron microscopy, and energy dispersive X-ray analysis show that calcium deposition is the prerequisite for phosphate ion deposition.
Abstract: The mechanism of apatite deposition on chemically treated Ti surfaces still is being studied. In this study, simulated body fluid, calcium aqueous solution, phosphate aqueous solution, and accelerated calcification solution are used as media to investigate the order of calcium and phosphate ion deposition on chemically treated Ti surfaces. The results of inductively coupled plasma spectra, scanning electron microscopy, and energy dispersive X-ray analysis show that calcium deposition is the prerequisite for phosphate ion deposition.
84 citations
TL;DR: In this paper, a biphasic catalytic system with water-soluble rhodium complex, RhCl(CO)(TPPTS) was studied and the results indicated that the hydroformylation occurred in the interface of aqueous/organic phases, where the formation of micelle was favorable for the reaction acceleration, and also favorable for an increase of linear aldehyde ratio in products.
Abstract: 1-Dodecene hydroformylation catalyzed by water-soluble rhodium complex, RhCl(CO)(TPPTS) 2 [TPPTS: P( m -C 6 H 4 SO 3 Na) 3 ], in the presence of surfactants and alcoholic solvents was studied. The results indicated that the hydroformylation in biphasic catalytic system occurred in the interface of aqueous/organic phases. The formation of micelle was not only favorable for the reaction acceleration, but also favorable for the increase of linear aldehyde ratio in products. The key factor of the enhancement of reaction rate was the richness of rhodium catalyst in the interlayer with the static electricity attraction between active rhodium anion species and cationic end of surfactant.
83 citations
TL;DR: In this article, an efficient recursive state estimator for dynamic systems without knowledge of noise covariances is suggested, which is called Extended Forgetting Factor Recursive Least Squares (EFRLS) estimator.
Abstract: An efficient recursive state estimator for dynamic systems without knowledge of noise covariances is suggested. The basic idea for this estimator is to incorporate the dynamic matrix and the forgetting factor into the least squares (LS) method to remedy the lack of knowledge of noises. We call it the extended forgetting factor recursive least squares (EFRLS) estimator. This estimator is shown to have similar asymptotic properties to a completely specified Kalman filter state estimator. More importantly, the performance of EFRLS greatly exceeds that of existing filtering techniques when the noise variance is misspecified. In addition, EFRLS also performs well when there is cross-correlation between the process and measurement noise streams or temporal dependencies within those streams. Some discussions and a number of simulations are made to provide practical guidance on the choice of an optimal forgetting factor and evaluate the performance of the EFRLS algorithms, which strongly dominates that of the standard forgetting factor recursive least squares (FRLS) and some misspecified Kalman filtering.
68 citations
TL;DR: In this article, a particle dynamics analyser (PDA), radial and axial velocity components and the size of solid particles in a hydrocyclone were measured, and the concentration distribution of the solid particles was obtained.
61 citations
61 citations
TL;DR: It is proved that a cooperative system cannot be permanent and for a permanent competitive system, the explicit expression of the permanent set E is obtained and sufficient conditions are given to guarantee the global attractivity of the positive equilibrium of the system.
Abstract: The permanence and global attractivity for two-species difference systems of Lotka-Volterra type are considered. It is proved that a cooperative system cannot be permanent. For a permanent competitive system, the explicit expression of the permanent set E is obtained and sufficient conditions are given to guarantee the global attractivity of the positive equilibrium of the system.
60 citations
TL;DR: The findings showed that the LG areas of the de novo glioblastomas exhibited numerous genetic aberrations, the proportion of which was increased in the HG areas, suggesting that these morphologically different cellular subsets were derived from a common transformed clone.
Abstract: Glioblastoma multiforme (GBM) often displays morphological heterogeneity in that low-grade (LG) area with well-differentiated cells are commonly found adjacent to high-grade (HG) area with poorly-differentiated cells. This heterogeneity may cause difficulty in obtaining representative tumor samples. Nevertheless, the genetic composition of these cells has only been occasionally examined. In the present study, we examined 29 de novo glioblastomas in which distinct LG and HG areas of sufficient volumes could be identified. These areas were microdissected from paraffin-embedded tissues and analyzed for genetic alterations: p53 mutations and immunohistochemistry; allelic losses at 17p13.1, 9p21, and 10q23-25; and amplification of the epidermal growth factor receptor (EGFR) gene and immunohistochemistry. We also examined 14 paired astrocytic tumors, in which a primary Grade II astrocytoma progressed over a period of time to a Grade III or Grade IV tumor. Our findings showed that the LG areas of the de novo glioblastomas exhibited numerous genetic aberrations, the proportion of which was increased in the HG areas. Genetic abnormalities seen in the LG areas were conserved in the HG areas suggesting that these morphologically different cellular subsets were derived from a common transformed clone. Also, the LG areas were genetically different from Grade II astrocytomas of the paired tumor group, in spite of their morphological similarity. In particular, the LG areas had more deletions on 10q23-25 (75% vs 20%, p = 0.04), but fewer p53 mutations (24% vs 71%, p = 0.003) and less p53 protein labeling (45% vs 79%, p = 0.04). These differences suggest that LG and HG areas in de novo glioblastoma are genetically closer to each other compared with paired low- and high-grade tumors that have progressed over time. Moreover, only a small proportion (17%) of our de novo glioblastomas exhibited EGFR amplification while a high proportion (62%) showed either p53 mutations or allelic loss of 17p13.1. We speculate that some de novo GBMs with copious LG areas may constitute a separate group with rapid progression from Grade II astrocytomas.
TL;DR: Bourque and Ligh as discussed by the authors proved that the conjecture is true for n ≤ ≤ 7 and not true for N ≤ ≤ ≤ ≥ 8, and thus the conjecture can be solved completely.
TL;DR: In this article, the authors used a k-e turbulence model to simulate the three-dimensional flow fields with a central air core in a hydrocyclone and showed that the predicted velocity profiles agree well with data measured by laser Doppler anemometry (LDA).
TL;DR: In this paper, coherent and incoherent combinations of off-axis Gaussian beams with rectangular symmetry have been studied in detail and analytical and numerical calculation results have been given to illustrate the propagation properties of the resulting beam through a first-order optical ABCD system.
01 Oct 1999
TL;DR: In this paper, the authors studied the influence of the uniform electric field on the electron transfer matrix element and the location of the avoided crossing in poly( p -phenylene) (PPP) oligomers.
Abstract: For the purpose of investigating the interchain electron transfer mechanism in poly( p -phenylene) (PPP), intermolecular electron transfer (ET) reactions between the parallel benzene cation radical and neutral benzene have been studied at the levels of 4-31G and DZP basis sets. The dependence of the ET matrix element V rp upon d , the distance between the two parallel donor and acceptor, has been elucidated. Considering the motion of charge carrier in external electric field, we have studied the influence of the uniform electric field on the electron transfer matrix element and the location of the avoided crossing. We have found that the one-electron Koopmans theorem can be applied to the estimation of the electron transfer matrix element, and that the position of the avoided crossing can be determined by pursuing the minimum MO energy-splitting factor. Conformations of PPP oligomers, up to 10 phenyl rings, have been optimized with AM1 semiempirical method. The torsion angle between two vicinity phenyl rings, and the ionization potential have been calculated and discussed.
TL;DR: Analytical expressions for the M(2) factor and the mode-coherence coefficients of hyperbolic-cosine- (cosh-) Gaussian beams have been derived and a simple method of producing cosh-Gaussian beams in an experiment, superposition of two decentered Gaussianbeam beams has been proposed.
Abstract: Analytical expressions for the M2 factor and the mode-coherence coefficients of hyperbolic-cosine– (cosh-) Gaussian beams have been derived, and a simple method of producing cosh-Gaussian beams in an experiment, superposition of two decentered Gaussian beams, has been proposed. Our results will be useful for studying more-general Hermite–sinusoidal-Gaussian beams.
TL;DR: The main result in this paper is that the category of fuzzy neighborhood spaces is isomorphic to that of fuzzifying topological spaces.
TL;DR: In this article, the authors derive a recursive formula for the number of ramified covering of a Riemann surface by RiemANN surface with elementary branch points and prescribed ramification type over a special point.
Abstract: Interpreting the number of ramified covering of a Riemann surface by Riemann surfaces as the relative Gromov-Witten invariants and applying a gluing formula, we derive a recursive formula for the number of ramified covering of a Riemann surface by Riemann surface with elementary branch points and prescribed ramification type over a special point.
TL;DR: A new class of random set-valued nonlinear generalized variational inclusions with noncompact-valued random fuzzy mappings is introduced with the aim of constructing a new iterative algorithm.
TL;DR: In this paper, the quantitative treatment of metallomicellar catalysis involving a ternary complex containing a ligand, metal ion, and substrate was proposed and the effect of pH on the reactivity was discussed.
Abstract: The quantitative treatment of metallomicellar catalysis involving a ternary complex containing ligand, metal ion, and substrate is proposed in this paper. The catalysis of the cleavage of p-nitrophenyl picolinate (PNPP) by the Cu 2+ -coordinating N-myristoyl-N-(β-hydroxyethyl)ethylenediamine in CTAB micelles was studied in aqueous buffer of pH ranging from 5.0 to 7.0 at 25 °C. The effect of pH on the reactivity is discussed. The result indicates that the 1:1 complex of the ligand and Cu 2+ is an active nucleophile in 0.01 mol.dm -3 CTAB micellar solution. The pK a of the hydroxyl group of the ternary complex was determined to be 6.52 in aqueous CTAB micelles. The rate constant, which shows the nucleophilic reactivity of ionized hydroxyl anion of the ternary complex toward PNPP, was determined to be k Nmax = 0.625 s -1 .
TL;DR: In this paper, the propagation of flattened Gaussian beams (FGBs) passing through a paraxial optical ABCD system has been studied in detail, where both unapertured and apertured cases have been considered.
TL;DR: In this paper, four methoxypolyethylene glycols (MPEG, molecular masses 350, 750, 2000 and 5000 Da), each activated by nitrophenyl chloroformate, were used to modify trypsin.
Abstract: Four methoxypolyethylene glycols (MPEG, molecular masses 350, 750, 2000 and 5000 Da), each activated by nitrophenyl chloroformate, were used to modify trypsin. Compared with the native trypsin, the MPEG-modified trypsin was more stable against temperature between 30 °C and 70 °C, longer chain of MPEG moiety corresponding to higher thermal stability. The T for the native and the modified trypsin (0.4 mg ml−1) was increased from 47 °C to 66 °C. The stabilization effect caused by MPEG modification was the result of decreasing in both the autolysis rate and the thermal denaturation rate. The thermodynamic analysis of the thermal denaturation process showed that the activation free energy (ΔG*) of the native and the modified trypsin at 60 °C was increased from 102.9 to 109.3 kJ mol−1; the activation enthalpy (ΔH*) was increased from 57.4 to 86.9 kJ mol−1; the activation entropy (ΔS*) was increased from −136 to −67 J molK−1. A possible explanation for the decreased thermal denaturation rate caused by MPEG modification was also discussed.
TL;DR: This paper gives a complete classification for minimal 2-spheres with constant Gaussian curvature immersed in the complex Grassmann manifold G(2,4).
Abstract: This paper gives a complete classification for minimal 2-spheres with constant Gaussian curvature immersed in the complex Grassmann manifold G(2,4).
TL;DR: In this paper, the existence of solutions and convergence of Mann and Ishikawa iterative processes for a class of variational inclusions with accretive type mappings in Banach spaces is studied.
Abstract: The purpose of this paper is to introduce and study the existence of solutions and convergence of Mann and Ishikawa iterative processes for a class of variational inclusions with accretive type mappings in Banach spaces The results presented in this paper extend and improve the corresponding results of [1–9]
TL;DR: In this article, the phase, composition and chemical states of elements at the tungsten surface were studied using X-ray diffraction and photoelectron spectroscopy (XPS).
TL;DR: In this article, the defect models of a low temperature centre and two high temperature centres were suggested by analysing the EPR spectra of, and the reasonableness of these models was discussed.
Abstract: By analysing the EPR spectra of , the defect models of a low temperature centre and two high temperature centres and are suggested. In centre , the ion replaces the ion and excess charge is compensated by two nearest vacancies on the same axis. In centres and , the vacancies below and above the ion are, respectively, dissociated from the low temperature centre . The suggestions are supported by the theoretical calculations of EPR parameters D, and for the three centres. The reasonableness of these models is discussed.
TL;DR: In this article, seven chiral lipophilic pyridyl-containing β-amino alcohol ligands have been synthesized by coupling of 6-alkoxymethyl-2-chloromethylpyridine 3 with the corresponding chiral β-AMino alcohols or l -cysteine.
Abstract: Seven novel chiral lipophilic pyridyl-containing β-amino alcohol ligands have been synthesized by coupling of 6-alkoxymethyl-2-chloromethylpyridine 3 with the corresponding chiral β-amino alcohols or l -cysteine. Their metal ion complexes have been investigated as catalysts for the enantioselective hydrolysis of N -protected α-amino acid esters in aqueous comicellar solution. The results indicate that the hydrophobic interactions between substrate and metallocatalyst, the rigidity of the ligand, the hydroxyl group of the ligand acting as a nucleophile for the transacylation process, and the micellar microenvironment are important factors for the activity and enantioselectivity. Large rate accelerations (up to three orders of magnitude) and moderate enantioselectivities (up to 7.81 (k R /k S )) employing 4a –Cu 2+ have been observed.
TL;DR: It is shown that the far-field expression of flattened Gaussian beams can be readily obtained by use of the derived expressions for the M(2) factor and field distribution.
Abstract: Explicit expressions for the M2 factor and field distribution of flattened Gaussian beams that propagate through an unapertured paraxial ABCD system are derived and illustrated with numerical examples. We show that the far-field expression of flattened Gaussian beams can be readily obtained by use of our results.
19 Jul 1999
TL;DR: A new Fourier transform profilometry based on modulation measurement based on MM that can measure the surface of a complex object in the same direction of projecting light has no the difficulties due to shadow and spatial discontinuity that exist in conventional FTP and also PMP methods.
Abstract: This article propose a new Fourier transform profilometry based on modulation measurement. We briefly call it FTP based on MM. Its main advantage is that it can measure the surface of a complex object in the same direction of projecting light, so it has no the difficulties due to shadow and spatial discontinuity that exist in conventional FTP and also PMP methods. In the paper, we give the principle of the method, the set-up of measurement system, and some primary experimental results. The results proved that this method is a promising method for acquiring 3D data of complex object.