Showing papers by "Xiamen University published in 2003"

Enhancement of antibody detection in cancer using panel of recombinant tumor-associated antigens.

Abstract: Cancer sera contain antibodies which react with a unique group of autologous cellular antigens called tumor-associated antigens (TAAs) This study determines whether a mini-array of multiple TAAs would enhance antibody detection and be a useful approach to cancer detection and diagnosis The mini-array of TAAs comprised full-length recombinant proteins expressed from cDNAs encoding c-myc, p53, cyclin B1, p62, Koc, IMP1, and survivin Enzyme immunoassay was used to detect antibodies in 527 sera from six different types of cancer Antibody frequency to any individual TAA was variable but rarely exceeded 15-20% With the successive addition of TAAs to a final total of seven antigens, there was a stepwise increase of positive antibody reactions up to a range of 44-68% Breast, lung, and prostate cancer patients showed separate and distinct profiles of reactivity, suggesting that uniquely constituted antigen mini-arrays might be developed to distinguish between some types of cancer Distinct antibody profiles were not observed in gastric, colorectal, and hepatocellular carcinomas with this set of seven TAAs Detection of autoantibodies in cancer can be enhanced by using a mini-array of several TAAs as target antigens Additional studies in early cancer patients and high-risk individuals and the design of unique antigen panels for different cancers would help to determine whether multiple antigen mini-arrays for the detection of autoantibodies might contribute a clinically useful noninvasive approach to cancer detection and diagnosis

Resistance distance and Laplacian spectrum

Abstract: The resistance distance r ij between two vertices v i and v j of a (connected, molecular) graph G is equal to the resistance between the respective two points of an electrical network, constructed so as to correspond to G, such that the resistance of any two adjacent points is unity. We show how the matrix elements r ij can be expressed in terms of the Laplacian eigenvalues and eigenvectors of G. In addition, we determine certain properties of the resistance matrix R=||r ij ||.

Overactivation of glycogen synthase kinase-3 by inhibition of phosphoinositol-3 kinase and protein kinase C leads to hyperphosphorylation of tau and impairment of spatial memory.

Abstract: Neurofibrillary tangles (NFTs) consisting of the hyperphosphorylated microtubule-associated protein tau are a defining pathological characteristic of Alzheimer's disease (AD). Hyperphosphorylation of tau is hypothesized to impair the microtubule stabilizing function of tau, leading to the formation of paired helical filaments and neuronal death. Glycogen synthase kinase-3 (GSK-3) has been shown to be one of several kinases that mediate tau hyperphosphorylation in vitro. However, molecular mechanisms underlying overactivation of GSK-3 and its potential linkage to AD-like pathologies in vivo remain unclear. Here, we demonstrate that injection of wortmannin (a specific inhibitor of phosphoinositol-3 kinase) or GF-109203X (a specific inhibitor of protein kinase C) into the left ventricle of rat brains leads to overactivation of GSK-3, hyperphosphorylation of tau at Ser 396/404/199/202 and, most significantly, impaired spatial memory. The effects of wortmannin and GF-109203X are additive. Significantly, specific inhibition of GSK-3 activity by LiCl prevents hyperphosphorylation of tau, and spatial memory impairment resulting from PI3K and PKC inhibition. These results indicate that in vivo inhibition of phosphoinositol-3 kinase and protein kinase C results in overactivation of GSK-3 and tau hyperphosphorylation and support a direct role of GSK-3 in the formation of AD-like cognitive deficits.

Time fractional advection-dispersion equation

Abstract: A time fractional advection-dispersion equation is obtained from the standard advection-dispersion equation by replacing the firstorder derivative in time by a fractional derivative in time of order α(0<α<-1). Using variable transformation, Mellin and Laplace transforms, and properties of H-functions, we derive the complete solution of this time fractional advection-dispersion equation.

Recursive Partitioning as an Approach to Selection of Immune Markers for Tumor Diagnosis

Abstract: Purpose and Experimental Design: Cancer sera contain antibodies which react with a unique group of autologous cellular antigens called tumor-associated antigens (TAAs), but the low frequency of positive reactions against any individual antigen has precluded use of autoantibodies as useful diagnostic markers. With enzyme immunoassay, we examined antibody frequencies to a panel of seven TAAs, c-myc, cyclin B1, IMP1, Koc, p53, p62, and survivin, in 527 cancer patients (64 breast cancer patients, 45 colorectal cancers, 91 gastric cancers, 65 hepatocellular carcinomas, 56 lung cancers, and 206 prostate cancers), and 346 normals. We used recursive partitioning to assess whether we could accurately classify individuals as either cancer patients or normals on the basis of the profile of antibody reactivity to the seven TAAs for each individual. Results: Recursive partitioning resulted in the selection of subsets of the seven-panel TAA, which differentiated between tumors and controls, and these subsets were unique to each cancer cohort. The classification trees had sensitivities ranging from 0.77 to 0.92 and specificities ranging from 0.85 to 0.91 in the cancer cohorts when normal means +2 SDs were used as standard cutoffs for immunoassay positivity. Antibody to cyclin B1 was the initial discriminating node for gastric and lung cancers, and for hepatocellular carcinoma, and was a subsequent discriminating node in all of the other cancer cohorts. c-myc was the initial discriminating node in breast cancer, p62 in prostate cancer, and IMP1 in colon cancer. Recursive partitioning demonstrated that no more than three of the seven TAAs were needed for any cancer cohort to arrive at these levels of sensitivity and specificity. Conclusions: This initial study shows that multiple antigen miniarrays can provide accurate and valuable tools for cancer detection and diagnosis. Performance of the miniarrays might be enhanced by other combinations of TAAs appropriately selected for different cancer cohorts.

Inhibitory Effects of Some Flavonoids on the Activity of Mushroom Tyrosinase

Abstract: Mushroom tyrosinase (EC 1.14.18.1) is a copper containing oxidase that catalyzes both the hydroxylation of tyrosine into o-diphenols and the oxidation of o-diphenols into o-quinones, and then forms brown or black pigments. In the present study, the effects of some flavonoids on the oxidation of L-3,4-dihydroxyphenylalanine (L-DOPA) have been studied. The results show that flavonoids can lead to reversible inhibition of the enzyme. A kinetic analysis showed that the flavonols are competitive inhibitors, whereas luteolin is an uncompetitive inhibitor. The rank order of inhibition was: quercetin > galangin > morin; fisetin > 3,7,4"-trihydroxyflavone; luteolin > apigenin > chrysin.

Policy and Practice of the Internationalization of Higher Education in China

Abstract: Directly motivated by the open-door policy, economic reforms and challenges from globalization and worldwide competition, as well as efforts to realize massification of higher education since 1978, the internationalization of higher education in China has experienced a change from activities concerning traditional outflows of international scholars, faculty members, and students before 1992 to those relating to trans-national higher education and internationalization of curricula. During the process, academic patterns from Europe, Asia, and the Pacific region as well as from America have significantly affected Chinese higher education. Internationalization has never been a one-way process; rather it comprises attempts to realize mutual communication or exchange, largely oriented and regulated by the government. The problem of increasing outflow of personnel abroad, the “brain drain,” as well as the ability to benefit from transnational education while also maintaininga national character remain key issues...

Rational Design and Fabrication of ZnO Nanotubes from Nanowire Templates in a Microwave Plasma System

Abstract: 通讯作者地址: Xie, SY (通讯作者), Xiamen Univ, Dept Chem, State Key Lab Phys Chem Solid Surfaces, Xiamen 361005, Peoples R China 地址: 1. Xiamen Univ, Dept Chem, State Key Lab Phys Chem Solid Surfaces, Xiamen 361005, Peoples R China

A Theoretical Exploration of the 1,3-Dipolar Cycloadditions onto the Sidewalls of (n,n) Armchair Single-Wall Carbon Nanotubes

Abstract: The viability of 1,3-dipolar cycloadditions of a series of 1,3-dipolar molecules (azomethine ylide, ozone, nitrone, nitrile imine, nitrile ylide, nitrile oxide, diazomethane, and methyl azide) onto the sidewalls of carbon nanotubes has been assessed theoretically by means of a two-layered ONIOM approach. The theoretical calculations predict the following: (i) other than the 18-valence-electron azomethine ylide and ozone, the 16-valence-electron nitrile ylide and nitrile imine are the best candidates for experimentalists to try; (ii) upon 1,3-dipolar cycloaddition, a 1,3-diople molecule is di-σ-bonded to a pair of carbon atoms on the sidewall of SWNT, forming a five-membered ring surface species; (iii) the as-formed 1,3-dipole-SWNT bonding is much weaker than that in the products of the molecular 1,3-DC reactions and can be plausibly broken by heating at elevated temperatures; (iv) the sidewalls of the armchair (n,n) SWNTs (n = 5−10) are subject to the 1,3-DCs of ozone and azomethine ylides; (v) both the ...

Highly active CNT-promoted Cu-ZnO-Al2O3 catalyst for methanol synthesis from H2/CO/CO2

Abstract: With types of in-house-synthesized multi-walled carbon nanotubes (CNTs) and the nitrates of the corresponding metallic components, highly active CNT-promoted Cu–ZnO–Al2O3 catalysts, symbolized as CuiZnjAlk-x%CNTs, were prepared by the co-precipitation method. Their catalytic performance for methanol synthesis from H2/CO/CO2 was studied and compared with the corresponding CNT-free co-precipitated catalyst, CuiZnjAlk. It was shown experimentally that appropriate incorporation of a minor amount of the CNTs into the CuiZnjAlk could significantly increase the catalyst activity for methanol synthesis. Under the reaction conditions of 493 K, 5.0 MPa, H2/CO/CO2/N2 = 62/30/5/3 (v/v), GHSV = 8000 h-1, the observed CO conversion and methanol formation rate over a co-precipitated catalyst of Cu6Zn3Al1-12.5%CNTs reached 36.8% and 0.291 μmol CH3OH s-1 (m2-surf. Cu)-1, which was about 44 and 25% higher than those (25.5% and 0.233 μmol CH3OH s-1 (m2-surf. Cu)-1) over the corresponding CNT-free co-precipitated catalyst, Cu6Zn3Al1. Addition of a minor amount (10–15 wt%) of the CNTs to the Cu6Zn3Al1 catalyst was found to considerably increase specific surface area, especially Cu surface area of the catalyst. H2-TPD measurements revealed that the CNTs and the pre-reduced CNT-promoted catalyst systems could reversibly adsorb and store a considerably greater amount of hydrogen under atmospheric pressure at temperatures ranging from room temperature to ∼573 K. This unique feature would be beneficial for generating microenvironments with higher stationary-state concentration of active hydrogen adspecies on the surface of the functioning catalyst, especially at the interphasial active sites since the highly conductive CNTs might promote hydrogen spillover from the Cu sites to the Cu/Zn interphasial active sites, and thus be favorable for increasing the rate of the CO hydrogenation reactions. Alternatively, the operation temperature for methanol synthesis over the CNT-promoted catalysts can be 15–20 degrees lower than that over the corresponding CNT-free contrast system. This would contribute considerably to an increase in equilibrium CO conversion and CH3OH yield. The results of the present work indicated that the CNTs could serve as an excellent promoter.

Performance analysis of an irreversible quantum heat engine working with harmonic oscillators.

Abstract: The cycle model of a regenerative quantum heat engine working with many noninteracting harmonic oscillators is established. The cycle consists of two isothermal and two constant-frequency processes. The performance of the cycle is investigated, based on the quantum master equation and semigroup approach. The inherent regenerative losses in the two constant-frequency processes are calculated. The expressions of several important performance parameters such as the efficiency, power output, and rate of the entropy production are derived for several interesting cases. Especially, the optimal performance of the cycle in high-temperature limit is discussed in detail. The maximum power output and the corresponding parameters are calculated. The optimal region of the efficiency and the optimal ranges of the temperatures of the working substance in the two isothermal processes are determined.

Activation of methane to syngas over a Ni/TiO2 catalyst

Abstract: Partial oxidation of methane (POM) to syngas and CH4/CO2 reforming have been investigated over a Ni/TiO2 catalyst in a fixed-bed reactor. The Ni/TiO2 catalyst has high initial activity but undergoes significant deactivation during the partial oxidation of methane reaction. Deactivation is due largely to the oxidation of Ni(0) to NiTiO3. After the partial oxidation of methane at 700 °C the catalyst was pale yellow. XRD confirmed that Ni(0) had been converted to NiTiO3 and oxygen pulse reactions found only traces of carbon were present after the POM reaction. The Ni/TiO2 catalyst has a high activity and a long term stability in the CO2 reforming reaction. XRD found Ni(0) was present after the reforming reaction but NiO and NiTiO3 were absent. Activation of methane over Ni/TiO2 was also investigated using pulse reaction techniques in the absence of gas phase oxygen. Methane pulse reactions demonstrated that the mechanism of methane oxidation changes as the oxidation state of nickel changes. CH4 may have been oxidized by oxygen from solid NiO or by active oxygen within the TiO2 support via the non-selective Rideal–Eley mechanism over the oxidized Ni/TiO2 catalyst surface. In contrast, CH4 is efficiently converted to CO and H2 via a direct oxidation mechanism when Ni/TiO2 is reduced. Pulse reaction studies provide evidence that the oxidation state of nickel controls the methane activation mechanism and the product distribution.

A study on pitting corrosion of aluminum alloy 2024-T3 by scanning microreference electrode technique

Abstract: Micropitting corrosion of aluminum alloy 2024-T3 was investigated by using scanning microreference electrode technique combined with scanning electron microscopy and X-ray energy dispersive spectroscopy. It was found that the micropitting initiated immediately after the exposure of Al 2024–T3 to NaCl solution at open-circuit potential. Some corrosion active nuclei developed with time while others disappeared. Most of the micropits were found to be associated with the second phase particles, specially the S phase particles (Al 2 CuMg). Three types of corrosion behavior of Al 2 CuMg were discussed.

Nanometer fluorescent hybrid silica particle as ultrasensitive and photostable biological labels

Abstract: Nanometer-sized fluorescent hybrid silica (NFHS) particles were prepared for use as sensitive and photostable fluorescent probes in biological staining and diagnostics. The first step of the synthesis involves the covalent modification of 3-aminopropyltrimethoxysilane with an organic fluorophore, such as fluorescein isothiocyanate, under N2 atmosphere for getting a fluorescent silica precursor. Then the NFHS particles, with a diameter of well below 40 nm, were prepared by controlled hydrolysis of the fluorescent silica precursor with tetramethoxysilane (TMOS) using the reverse micelle technique. The fluorophores are dispersed homogeneously in the silica network of the NFHS particles and well protected from the environmental oxygen. Furthermore, since the fluorophores are covalently bound to the silica network, there is no migration, aggregation and leakage of the fluorophores. In comparison with common single organic fluorophores, these particle probes are brighter, more stable against photobleaching and do not suffer from intermittent on/off light emission (blinking). We have used these newly developed NFHS particles as a fluorescent marker to label antibodies, using silica immobilization method, for the immunoassay of human alpha-fetoprotein (AFP). The detection limit of this method was down to 0.05 ng mL(-1) under our current experimental conditions. We think this material would attract much attention and be applied widely in biotechnology.

Spectral and Pseudospectral Approximations Using Hermite Functions: Application to the Dirac Equation

Abstract: We consider in this paper spectral and pseudospectral approximations using Hermite functions for PDEs on the whole line. We first develop some basic approximation results associated with the projections and interpolations in the spaces spanned by Hermite functions. These results play important roles in the analysis of the related spectral and pseudospectral methods. We then consider, as an example of applications, spectral and pseudospectral approximations of the Dirac equation using Hermite functions. In particular, these schemes preserve the essential conservation property of the Dirac equation. We also present some numerical results which illustrate the effectiveness of these methods.

Phase transformation mechanism between γ- and θ-alumina

Abstract: \ensuremath{\gamma}-alumina transforms to \ensuremath{\theta}-alumina and finally to \ensuremath{\alpha}-alumina in the sequence of thermal dehydration of boehmite. We report a detailed theoretical investigation of the \ensuremath{\gamma}- to \ensuremath{\theta}-alumina transformation based on first-principles density-functional calculations. Although the unit cells of cubic \ensuremath{\gamma}-alumina and monoclinic \ensuremath{\theta}-alumina look quite different, we have identified cells for both the polytypes (with the composition ${\mathrm{Al}}_{16}{\mathrm{O}}_{24})$ that look very similar and can be continuously transformed one to another. The transformation may be described by a set of aluminum atom migrations between different interstitials while the oxygen atoms remain fixed. Total-energy calculations along the paths of the atomic migrations have been used to map out possible transformation pathways. The calculated conversion rate accurately predicts the experimentally measured transformation temperature. The deduced orientation relationships between the \ensuremath{\gamma}- and \ensuremath{\theta}-alumina forms also agree with experimental observations. The formation of several different interfaces observed in domain boundaries of \ensuremath{\theta}-alumina may correspond to different migration paths of the aluminum atoms in neighboring domains during the \ensuremath{\gamma}- to \ensuremath{\theta}-alumina phase transition.