Showing papers by "Nanchang University published in 1998"

Photocatalytic reduction of nitrate ions on TiO2 by oxalic acid

Abstract: Using oxalic acid as a hole scavenger, the photocatalytic reduction of nitrate in aqueous dispersions of TiO 2 has been investigated. Oxalic acid accelerates the reaction considerably compared to the reaction in the absence of oxalic acid. In the presence of nitrate, the oxidation of oxalate is also accelerated. The reduction product of the nitrate is mainly ammonia. The effects of concentrations of nitrate, of oxalate, and of pH were studied. The adsorption of the reactants on TiO 2 is an important factor for accelerating the reaction.

Genetic variation in sympatric Ascaris populations from humans and pigs in China.

Abstract: It has recently been shown using genetic markers that Ascaris in humans and pigs in Central America comprise reproductively isolated populations. We present a similar analysis for a region of China in which close association between pigs and humans has been the norm for thousands of years, and agricultural practices will result in frequent exposure to eggs from both sources. DNA fragments from selected regions of mitochondrial and ribosomal DNA were amplified by PCR and allelic forms identified following digestion with a panel of restriction enzymes, using DNA from a total of 115 individual worms from both people and pigs from 2 neighbouring villages. Significant frequency differences in both mtDNA haplotypes and the rDNA spacer were found between the 2 host-associated populations, indicating that they represented reproductively isolated populations. Mitochondrial haplotype frequencies were different from those observed in Guatemala and also from other Asian Ascaris populations, suggesting low levels of gene flow between populations. However, we found no evidence for significant heterogeneity in the genetic composition of Ascaris infrapopulations in either humans or pigs, possibly indicative of agricultural practices in China which have resulted in a random distribution of alleles within the parasite populations.

Effect of green tea and black tea on the metabolisms of mineral elements in old rats.

Abstract: A 2-mo experiment with the white Sprague-Dawley (SD) rats was conducted to investigate the effect of the water extracts of black tea (BTWE) and green tea (GTWE) and the black tea leaves (BTF) and the green tea leaves (GTF) on the metabolism of mineral elements. One hundred eight 12-mo-old white SD rats were randomly divided into 13 groups; 6 of these drank the BTWE or GTWE in which the water extracts concentrations of black tea or green tea were, respectively, 0.6%, 1.2%, and 2.4%, and 6 of these had black tea leaves (BTF) and green tea leaves (GTF) added in which the contents of BTF or GTF were, respectively, 0.5%, 1.0%, and 2.0%, one of these was control. The teas and their water extracts could promote the absorption of manganese and copper. In GTF, BTF, GTWE, and BTWE, the apparent absorption rates of manganese were significantly increased. The manganese contents in the tibia were also elevated, and the differences between GTWE and GTF were significant. The apparent absorption rates of copper and the copper contents in the tibia were increased, but not significantly. The teas and their water extracts inhibited the absorption of calcium (p > 0.05) and iron (p 0.05) and cerebrum (p < 0.05) were increased. GTF and GTWE decreased the apparent absorption rates of zinc, but BTF and BTWE increased them; the zinc contents in tibia were a little improved, whereas its contents in the cerebrum were gradually decreased with the increase of tea leaves dose and tea concentration.

Existence theorems for the Schro¨dinger equation involving a critical Sobolev exponent

Abstract: In this paper we establish the existence of a solution of the Schrodinger equation (1). The existence of a solution is obtained by a variational method based on the critical point theorem 2.4 from [3].

The mechanism of formation of TiB(2) particulates prepared by in situ reaction in molten aluminum

Abstract: By making use of a novel technique in which TiB(2) particulates are fabricated by an in situ reaction in molten aluminum, we have successfully produced TiB(2)/Al composites. In order to reveal the characteristic of the technique, the mechanism of formation of TiB(2) particulates obtained by this method is studied in this article. Both theoretical and experimental results have shown that the TiB(2) particulates are formed by a diffusion mechanism when the molar fraction of aluminum in the preform is higher than 43.5 pet. In this case, the TiB(2) particulates are generally spherical, and their mean size is less than 2.0 mu m. On the contrary, the TiB(2) particulates are formed by a solution-precipitation mechanism when the fraction is lower than 43.5 pet. In this case, the TiB(2) particulates are multifaceted, and the size of most particulates lies between 3.0 and 6.0 mu m.

Effect of oral aluminum and aluminum citrate on blood level and short-term tissue distribution of aluminum in the rat.

Abstract: Aluminum (Al) absorption seems to be very low, but many factors can enhance it in animals and humans. In the present study, we investigated the acute effect of Na citrate on Al absorption by monitoring Al levels in blood and several tissues. For this purpose, 18 Wistar male rats were divided into 3 groups: control, Al, and Al + Na citrate. After a 14-h fasting period, animals were dosed orally with deionized water, or 2 mmol Al chloride, or 2 mmol Al chloride plus 2 mmol Na citrate. Blood samples were taken before and 1, 2, 4, and 6 h after the gavage. Al concentrations in blood, liver, tibia, kidney, and intestinal wall were determined by ICP-OES. In the Al and Al + citrate groups, Al blood concentrations peaked at 1 h and 2 h with higher levels in the Al + citrate group. Al gavage resulted in an increase in Al level in intestinal wall, but not in the other investigated tissues. Simultaneous gavage of citrate with Al significantly increased its tissue levels in tibia, kidney, and in intestinal wall. Our data show clearly that Al as chloride can be absorbed, but not well retained by the organism tissues. Furthermore, the model used in the present study is appropriate for acute studies to investigate the effect of various compounds on Al absorption in the rat.

The OI-Resolution of Operator Rough Logic

Abstract: Based on rough set theory, this paper establishes operator space [ξ*, ξ*]. It is also a subset on truth value interval [0,1]. The operators is put in the front of the formulas to produce the manyvalued logic called operator rough logic(ORL). It defines OI-valid and OI-inconsistent, OI-resolution of the logic, where OI is an abbreviation of Operator Interval. And it also proves the soundness theorem of the logic resolution.

Adhesion modification in (Cu, Nb, Ti)/SiO2 pairs by argon ion bombardment

Abstract: We have investigated adhesion enhancement of the (Cu, Nb, Ti)/SiO2 interface evaporated at room temperature and 300°C by Ar ions bombardment to various doses. The experimental results showed that the adhesion strength increased after bombardment at a threshold dose and then saturated at higher doses in all pairs. The increment of the adhesive strength increases with the increasing of the nuclear energy loss (dE/dx)n at the interface between metal films and oxide substrates. The threshold doses decrease with the increasing of the nuclear energy loss (dE/dx)n at the interface between metal films and oxide substrates. The possible mechanism involved during ion beam processing is discussed in this paper.

Formation of nodular defects as revealed by simulation of a modified ballistic model of depositional growth

Abstract: Nodular defects appear frequently in deposited films and coatings, especially in those deposited under higher deposition rate and lower substrate temperature. In order to understand the mechanism and to predict the effects of process parameters, a modified two-dimensional ballistic model of deposition growth has been developed and programmed for computer simulation. In this model, both scattering of depositing particles and surface diffusion of deposited particles are allowed. Simulated experiments have been carried out with respect to the effects of deposition rate, surface diffusivity of deposited particles, degree of scattering of depositing particles and presence of substrate asperities. Morphological features of the nodular defects are reproduced by the simulation. The results show that higher deposition rate, lower surface diffusivity of deposit and higher degree of scattering of depositing particles favour formation of nodular defects. Asperities on substrate are found usually responsible for formation of nodular defects; however, under favourable conditions, nodular defects can form without presence of any substrate asperity. © 1998 Chapman & Hall

Real-time measurement of temperature field with ICCD as sensor (I)──Principle and method for division of temperature range

Abstract: Real time measurement of temperature field can be achieved by colorimetric method using ICCD as sensor However, due to limited dynamic response range of the ICCD, the measurable range of temperature is very small In order to expand the temperature measuring range, a device was developed which can take several two color images with different shutoff times subsequently within very short time First, the principle of real time measurement of temperature field with two color thermal images is introduced Then theoretical analysis on this method, including determination of various parameters, such as shutoff time, number of temperature range, wavelength of the colors, etc is described Experiments were conducted, which proved that theoretical analysis coincides with the experimental results

The luminescence of LaSi2−x formed by ion beam synthesis in (1 1 1) silicon wafer

Abstract: The structure and luminescence of compound layer formed by 45–180 keV La ion implantation on (1 1 1) silicon substrate have been investigated. X-ray diffractometer (XRD) was used to determine the phase structure formed in ion beam synthesis. A fluorescence photospectrometer was used to measure the photoluminescence (PL). The results show that LaSi2−x compounds have been formed directly during the ion implantation. The samples exhibited intensive luminescence and up-conversion luminescence at room temperature (RT). Their PL intensity decreased with increasing of the excitation wavelength in the range from 220 to 250 nm. On the other hand, their PL intensity increases with increasing of the excitation wavelength between 600 and 700 nm. The LaSi2−x films have been found to have a very high efficiency of up-conversion from red to blue-violet.

Low-cycle impact fatigue of SiCw/7475Al composite

Abstract: Important uses in the future for metal-matrix composites are in aerospace, weaponry, and high-speed power plants in which the inertial force produced by great acceleration is a load of high strain rate. Therefore close attention is given to the mechanical behavior of a composite at high strain rates. This paper reports a study of the behavior and mechanisms of a SiC w /7475 composite in low-cycle impact fatigue (LCIF). The LCIF and impact tension tests were conducted by using the push-pull impact fatigue apparatus developed by the authors, in which the loading assembly was actually a combination of a Hopkinson’s pressure bar and an extension bar. In the apparatus the trapezoidal stress wave loads were produced. The strain rates in specimens may reach 400 s -1 .The results show that for a SiC w /7475 composite, the strain-rate effects on yield stress, ductility, cyclic hardening and softening, δ e /2-N f relation, and transition life were slight. In low-cycle impact fatigue the cracks often initiated within or near the SiC particles, which mingled in the composite. The SiC w /7475 composite was found to be less ductile than its alloy matrix; in low-cycle fatigue brittleness appears. Therefore great attention must be given to the behavior of the composite when it is used as a structural material.

Studies on the surface behavior of non-chromium type high temperature co shift catalysts

Abstract: The activity of an iron-base catalyst modified by molybdenum and cerium for CO shift reaction was investigated in a flow microcatalytic reactor. The results show that the activity of the modified catalyst is obviously improved. The surface behavior of Fe−Mo−Ce catalyst and the role of molybdenum and cerium in the catalyst are discussed.

A (p,q)-Deformation of Quantum Mechanics*

Abstract: On a one-dimensional lattice with a geometric sequence spacing, the Hermitian conjugation of a (p,q)-derivative operator is discussed by means of (p,q)-integration. Then a (p,q)-deformation of both the Heisenberg algebra for the canonical coordinates and the Heisenberg–Weyl algebra for the harmonic oscillator is presented. It is shown that although in the algebraic aspect the (p,q)-deformation discussed here is identical with q-deformation given by Truong, the (p,q)-deformed Schrodinger picture is in fact different from the q-deformed one.

Holomorphic 2-spheres in Grassmann manifolds

Abstract: A generalized Frenet formula for holomorphic 2-spheresS 2 in Grassmann manifoldsG(k,n) is introduced and a generalized Pliicker formula is achieved. By use of these formulae some pinching theorems for Gaussian curvature are obtained which generalize the corresponding results about holomorphic and minimalS 2 inCP n-1. Einsteinian holomorphic subbundle of the trivial bundleS 2 ×C n is investigated.

Fourier transform moire deflectometry

Abstract: Fourier transform technique for moire deflectogram is proposed to automatically map the phase object. The moire deflectogram is generate by conventional deflectometer and is analyzed by means of Fourier transform algorithm, in which the fringe phase is retrieved and phase object message is obtained automatically. Theoretical analysis, simulation calculation and application example are presented.

Real-time measurement of temperature field with iccd as sensor (ii) : principle and method for optimum design of wavelength

Abstract: The colorimetric method for real-time measurement of temperature field using ICCD as sensor was developed. In order to ensure the accuracy and sensitivity, the relationship between the ratio response of two-color images and radiant property of body, transmission property of filter, spectral response of ICCD is discussed. The analysis is based on computer calculation of the established mathematical model. On the basis of the analysis, optimum wavelengths are obtained for a given sensor system. Experimental work was carried out to check the correctness of the theoretical results. The method is useful for general purpose of study and design of the developed system.

New method of two-color calibration and one-color measurement for real-time inspection of temperature field

Abstract: Based on the research of a colorimetric method with tow RI images, a new method of two-color calibration and one-color measurement for real-time inspection of welding temperature field was developed, which can not only eliminate disadvantages of one-color measuring method, such as dependence of the measured temperature on the distance of object and the emissivity of object and the parameters of the measurement system, but also overcomes disadvantages of two-color measuring method, such as the low speed and sensitivity on the noise in the measurement. The method is applied successfully in welding temperature field measurement, the measuring time is less than 0.5 second per temperature field and the error of measurements is within 30 degrees C. Weld shape control is another important application of the developed method. Using the width of isotherm from welding temperature field as input and welding current as control parameter, a penetration control system for TIG weld was installed. Experiments proved that the even penetration be obtained under very unstable weld condition.© (1998) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

New adjustment method of transformer taps in power flow

Abstract: An adjustment method for the voltages on two sides of power transformer taps is presented. A large number of data indicate an approximate proportional change in voltage regularity of on the two sides of power transformer taps with changes of tap ratios. The method can automatically modify the adjustment volume of tap ratios according to the former adjustment results. The adjustment accuracy of the voltage can reach a range within /spl plusmn/0.001.

Determination of Ultra Trace Amounts of Selenium(IV) by Means of a New Reaction System —Methyl Yellow and Hydrogen Peroxide

Abstract: A spectrophotometric method for the determination of selenium is described, based on the selenium(IV)-catalyzed oxidation of methyl yellow with hydrogen peroxide in a nitric acid medium. As the redox reaction proceeds, the red color of methyl yellow is decolorized. The values of logA0/A show a good linear relationship with the amounts of selenium (A0: absorbance of uncatalyzed reaction solution; A: absorbance of catalyzed reaction solution.). The new method is extremely sensitive, as little as 2 × 10−10 g ml−1 can be easily measured. The detection range is from 5 × 10−7 to 2 × 10−10 g ml−1. In addition, the system possesses extremely high selectivity, most of ions including copper and tellurium can be tolerated during the determination of selenium. The method has been used to determine selenium in egg and wheat, and satisfactory results were obtained.

Inspecting the microprofile and defects of optical surfaces using an atomic-force microscope

Abstract: In this paper , an Atomic Force Microscope( AFM) with laser lever and it ' s application in specting microprofile of optical surface are presented. The nanometer-grade defects in optical and supersmooth surface can be tested byAFM. The microprofile drawings have the accuracy higher than (0 . 1 mm) in both vertical and lateral resolu-tion. Some testing results of optical and supersmooth surfaces are shown in the paper. Keywords : defect of optical surface; microprofile drawing; optical inspecting 1.. INTRODUCTION The roughness inspecting of optical surface use to be made by inteference method, as the double focus intefer-ence profile testing method[1 • The inteference method has the vertical resolution better than 0. 1 nm and the lateralone better than 2pm. But some researchs represents, these methods have a good vertical resolution but a poor lateral one. Without these , one developed some new methods for optical surface inspecting , as using a microdensitometer[21or CCD camera3 to analyzer electron micrographs of shadowed-surface replicas.

A problem about the weak Hilbert property

Abstract: In this paper, we prove the main result: Let both (K, S) and (K*,S*) be preordered fields, and let (K*,S*) be a finitely generated extension of (K, S). IfK* is transcendental overK, then (K*,S*) has the weak Hilbert property. This result answers negatively an open problem posed by the author in reference [1]. Moreover, some results on the weak Hilbert property are established.

Selective synthesis of dimethylamine over rare earth modified mordenites

Abstract: The selective synthesis of dimethylamine from ammonia and methanol over the rare earth modified mordenites in a fixed bed reactor was studied. A mordenite, NaM, was modified by different rare earth elements, such as Ce, Gd and Y, with cation-exchange method. The experimental results show that various modified mordenites have better catalytic properties compared to the unmodified mordenites. The Ce 4+ modified mordenite, prepared by treating with a solution of 0 1 mol/L Ce 4+ and calcining at 600℃ for 2～3 h after moulded with a binder (bentonite), exhibits both high conversion of methanol and selectivity to DMA, up to 99 8% and 50 3%, respectively, at 400℃ and under ambient pressure, and has an improved stability against coking. The effects of the kind of rare earth elements, the content of Ce 4+ in the solution, and the conditions of calcining and moulding on the catalytic properties and the structural characteristics of the rare earth cation exchanged mordenites have been discussed in detail.

Absorption spectrum properties of BLM

Abstract: In this paper, an optical fiber spectrometer is used to measure the properties of absorption of p-BLM at visible range. The formation and collapse of p-BLM has been observed. According to the ration of decreasing in the light intensity transmitted through p-BLM at a certain wavelength, the average lifetime of p-BLM can be estimated.© (1998) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.