In the past Wei Li has collaborated on articles with Dirck L. Dillehay and Zheng H. Yu. One of their most recent publications is Discussion on “On-line determination of bromide ion in spent brine”. Which was published in journal Analytica Chimica Acta.

More information about Wei Li research including statistics on their citations can be found on their Copernicus Academic profile page.

Wei Li's Articles: (1256)

Discussion on “On-line determination of bromide ion in spent brine”

AbstractSome errors in the mathematical treatment of a dual-cell system in the paper “On-line determination of bromide ion in spent brine” [Anal. Chim. Acta, 256 (1992) 97] were found and some necessary corrections to the mathematical treatment have been made.

Discussion on “On-line determination of bromide ion in spent brine”

AbstractSome errors in the mathematical treatment of a dual-cell system in the paper “On-line determination of bromide ion in spent brine” [Anal. Chim. Acta, 256 (1992) 97] were found and some necessary corrections to the mathematical treatment have been made.

Discussion on “On-line determination of bromide ion in spent brine”

AbstractSome errors in the mathematical treatment of a dual-cell system in the paper “On-line determination of bromide ion in spent brine” [Anal. Chim. Acta, 256 (1992) 97] were found and some necessary corrections to the mathematical treatment have been made.

Discussion on “On-line determination of bromide ion in spent brine”

AbstractSome errors in the mathematical treatment of a dual-cell system in the paper “On-line determination of bromide ion in spent brine” [Anal. Chim. Acta, 256 (1992) 97] were found and some necessary corrections to the mathematical treatment have been made.

Discussion on “On-line determination of bromide ion in spent brine”

AbstractSome errors in the mathematical treatment of a dual-cell system in the paper “On-line determination of bromide ion in spent brine” [Anal. Chim. Acta, 256 (1992) 97] were found and some necessary corrections to the mathematical treatment have been made.

Characterization of neuropeptide Y (NPY) receptors in human hippocampus

AbstractWe identified a 50 kDa neuropeptide Y (NPY) receptor from human hippocampus by affinity labeling. NPY specific binding and labeling of the receptor were inhibited in parallel by increasing concentrations of unlabeled NPY (IC= 0.27nM and0.18nM, respectively). Peptide YY (PYY), but none of the pancreatic polypeptides, was as effective as NPY in displacing [125I]NPY. NPY fragments inhibited binding with the rank order of potency: NPY>NPY13–36 >NPY20–36≥NPY18–36 >NPY1–36free acid≥NPY26–36. These results demonstrate that the human hippocampal NPY receptor is a 50 kDa protein fitting the classification of a Y2 receptor subtype.

In vitro effects of retinoids on murine thymus-dependent and thymus-lndependent mitogenesis

AbstractThe effects of three retinoids: all-trans-retinoic acid (RA), 13-cis-retinoic acid (13-cis-RA), and N-(4-hydroxyphenyl)retinamide (4-HPR) on murine splenic lymphocyte proliferative responses to mitogens were evaluated. The responses to T-cell mitogens, PHA and Con A, and a T-cell-dependent B-cell mitogen, PWM were significantly potentiated by these retinoids. However, proliferative responses to a B-cell mitogen, Escherichia coli LPS were unaffected or inhibited. All three retinoids at concentrations ranging from 10−6 to 10−15M significantly potentiated Con A-induced proliferative responses. In response to PWM, 10−13M RA, 10−12M 13-cis RA, and 10−11M 4-HPR were the lowest concentrations producing significant potentiation. Endpoint concentrations of retinoids significantly potentiating responses to PHA were; 10−9M RA, 10−8M13-cis RA, and 10−6M 4-HPR. These responses were independent of retinol contained in fetal calf serum supplemented medium since responses were reproduced in serum-free medium devoid of retinol. Optimal potentiation by retinoids of responses to these T-cell-dependent mitogens were found at superoptimal concentrations of mitogen suggesting a selective inhibition of T-suppressor cells. Thus, potentiation of T-cell-dependent mitogen responses provides the most sensitive biological assay yet described for detection of retinoid activity and is a reproducible system to explore the cellular and molecular mechanisms of retinoid-mediated immunopotentiation.

State estimation based model predictive control applied to shell control problem: a case study

AbstractIn this paper, we demonstrate how a practical control problem with multiple control/optimization objectives and various operating constraints is formulated in the theoretical framework of state estimation based model predictive control (SEMPC) proposed by Lee . We use the shell control problem (SCP) of a heavy oil fractionator as case study. The shell control problem embodies most of the critical elements of challenging industrial process control problems (e.g. unmeasured disturbances, model uncertainty, input/output constraints, optimization objective conflicting with control requirements, failure-prone sensors, secondary measurements, nonsquare system, etc.) and therefore serves as a good test problem for investigation of potential benefits and pitfalls of the new technique. We demonstrate in the case study that, while the theory for the new model predictive control (MPC) technique is rigorously laid out, it is nontrivial for practicing engineers to formulate various practical objectives correctly within the theoretical framework to realize all the potential performance improvements of SEMPC over conventional MPC. By formulating and analyzing a series of different SEMPC controller designs for SCP, this paper highlights some of the possible difficulties that engineers may encounter in applying SEMPC to practical control problems and shows how these difficulties are overcome most efficiently.

Phase behavior in thermotropic liquid crystalline polymer and polyarylethersulfone blends

AbstractAn experimental study of the phase morphology and miscibility of binary blends of polyarylethersulfone (PES) and a liquid crystalline polymer (LCP) of p-oxybenzoate and ethylene terephthalate units in a 60/40 molar ratio (PET-60PHB) is described. Blends were prepared by solution coprecipitated and compression-molded methods. Differential scanning calorimetry (DSC) and dynamic viscoelastometer (DDV) indicated the blends are partially compatible, because two glass transition temperatures corresponding to the two components were observed. These findings were confirmed by scanning electron microscopy. Phase inversion in blends was observed, when the blends contained 50 wt% or more of the LCP.

Research paperIron in human atheroma and LDL oxidation by macrophages following erythrophagocytosis

AbstractThe oxidative modification of low density lipoprotein (LDL) has been implicated as an early step in the formation of atheromatous lesions. In vitro studies suggest it to be accelerated, or even initiated, by transition metals such as iron or copper in combination with a reducing agent. Even if such metals have been demonstrated in atheroma gruels, their origin and precise localisation within human atheroma are presently unknown. In the initial part of this study we applied Pearl's method, energy dispersive X-ray microanalysis, and a modified Timm sulphide silver method (SSM) to demonstrate the occurrence of iron in early atherosclerotic lesions from a number of consecutive autopsy cases with evident, general atheromatosis. With the very sensitive SSM, but not with the other techniques, we found foam cells to contain heavy metals with a mainly lysosomal localization. On the basis of the hypothesis that such a lysosomal accumulation of iron might be due to erythrophagocytosis by migrating tissue-bound macrophages that later develop into foam cells, we designed an in vitro model system where human monocyte-derived macrophages were exposed to artificially aged, UV-exposed erythrocytes. The macrophages were then exposed to LDL in serum-and iron-free RPMI medium, occasionally in the presence of the potent iron-chelator desferrioxamine. The capacity of macrophages to oxidise LDL was much enhanced following erythrophagocytosis, and the process was shown to involve secretion of iron. Consequently, LDL oxidation was greatly inhibited by desferrioxamine. We conclude that iron may be exocytosed by macrophages that previously had their lysosomal apparatus enriched with iron, e.g. due to erythrophagocytosis. Oxidation of LDL may result in ensuing foam cell-formation secondary to scavenger-receptor mediated endocytosis by macrophages.

Electronic materialA two-stage method for growing large single crystals of diamond with high quality

AbstractA novel method is reported for growing large single crystals of diamond at high pressure and high temperature using a metallic solvent, by which high-quality crystals can be grown with a larger net growth rate. The growing space has a recess at its lower temperature side, and the seed crystal is located at the bottom of the recess. The seed grows to fill the recess, and its extended top surface serves as a large seed for the second-stage growth. The main part of the crystals grown in the second stage is found to have no or only few metallic inclusions when the size of the recess is selected appropriately. Experimental results show that the growth rate is small for the first-stage growth within the recess, but it becomes larger after the crystal grows out of the recess. The diffusion field of carbon in the solvent is simulated by numerical calculation, and the results can reasonably explain this nature of the growth process.

Section 14. Interfaces and multilayerVisible electroluminescence from crystallized a-Si:H/a-SiNx:H multiquantum well structures

AbstractVisible photoluminescence (PL) in crystallized a-Si:H/a-SiNx:H multiquantum well (MQW) structures is reported for the first time. In this paper new results are presented on visible electroluminescence (EL) from these novel luminescent structures. The MQW heterostructures consisting of 40 layers were formed by PECVD method and then crystallized by Ar ion laser annealing technique. The crystallized samples with well layer thickness, LS = 4 nm, showed an intense visible PL peaked ∼ 2.0 eV. The experimental EL cells are of the form of semitransparent metal/crystallized a-Si:H/a-SiNx:H MQWs/p+-a-Si:H/quartz substrate. When the forward current density reaches a certain value, stable visible (orange) light is observed by the naked eye. A possible explanation of this light emission is the radiative recombination due to the carriers injection into quantized states in nano-size Si crystallites within the Si potential wells.

Section 19. Sensors and other devicesThe fabrication and application of a novel OASLM based on a-Si:H and its alloy

AbstractThe fabrication and operation of an optically addressed spatial light modulator (OASLM), consisting of a hydrogenated amorphous silicon (a-Si:H) p-i-n photodiode as the photosensor, a twisted nematic liquid crystal as the electro-optical modulating material and a hydrogenated amorphous silicon germanium layer (a-SiGex:H) as the light blocking material are described. The a-Si:H p-i-n diode and a-SiGex:H are deposited continuously in one reactant chamber by means of plasma enhanced chemical vapor deposition (CVD) methods with a shutter. The electric and optical characteristics were measured. Under a 300 lux illumination of white light, the OASLM exhibits a resolution of at least 20 line pairs/mm and a contrast ratio of more than 25:1. The writing sensitivity is about 3 lux. Finally, an attempt is made to realize optical logical processes using our OASLM. In one experimental system, sixteen real-time optical logical operations of two binary-state images are achieved.

On the Jacobian conjecture: a new approach via Gröbner bases

AbstractIn this paper we propose a new approach to the Jacobian conjecture via the theory of Gröbner bases. We give a Gröbner base criterion for a polynomial map to be polynomially invertible. Using this and using a result of Bass concerning the inverse degrees of automorphisms of polynomial rings, we reduce the Jacobian conjecture to certain problems in the complexity theory of Gröbner bases. As a by-product, we construct examples which show the non-existence of a universal bound of degrees of Gröbner bases over a polynomial ring in one variable over a field.

On a problem about face polynomials

AbstractIt is proved that an R-automorphism of polynomial ring R[x1,…,xn] is completely determined by its face polynomials, where R is a reduced commutative ring and n≥2. An example is given which shows that the condition R being reduced cannot be weakened.

1. Science and technology of intermetallicsRare-earth-transition-metal-boron permanent magnets with smaller temperature coefficients☆

AbstractRare-earth-transition-metal-boron permanent magnets with smaller temperature coefficients α have been studied by replacing neodymium and iron in the Nd-Fe-B alloy with the heavy rare earth elements dysprosium and cobalt respectively. The average reversible temperature coefficient of the magnet can be decreased from −0.116% °C−1 (20–100 °C) to −0.028% °C−1 (20–100 °C), lower than that of SmCo5 magnets. The influence of these partially replaced elements upon the magnetic properties of magnets and their temperature stability are discussed. The Curie temperature Tc may be increased significantly by partial replacement of iron in Nd-Fe-B alloy by cobalt, and the reversible temperature coefficient decreases with increasing amount of cobalt. Because of the increasing Tc, the σ-T curves are extended and flattened. Partial replacement of neodymium in Nd-Fe-Co-B alloy by dysprosium, not only increases the intrinsic coercive force (iHc) of the magnet, but also plays the role of temperature compensation, and hence further decreases the temperature coefficient a, since the HRE-Fe-Co-B compounds (HRE ≡ Gd, Dy, Ho and Er) are ferrimagnetic.

Gonadotropin-releasing hormone (GnRH) and cyclic amp positively regulate inhibin subunit messenger RNA levels in human placental cells

AbstractBioactive and immunodetectable levels of both inhibin and activin are present in the placenta, raising questions as to the regulatory control of their synthesis. This study was designed to determine the effect of cyclic AMP (cAMP) and gonadotropin-releasing hormone (GnRH) on inhibin subunit gene expression in short-term incubations of placental cells. A semi-quantitative polymerase chain reaction (PCR) technique was used after isolation of total RNA and first strand cDNA synthesis from mechanically dispersed trophoblast-enriched cells obtained from human placentae at term. The level of gene expression of inhibin subunits was higher for βA and α-subunits mRNA compared to the βB-subunit mRNA as determined by PCR in combination with Southern blotting or Northern hybridization. Steady-state levels of β-actin mRNA did not change throughout the 6-h incubation period and was used as a control of PCR amplification of the respective inhibin subunit gene transcripts following treatments with 8-bromo cAMP or GnRH. 8-bromo cAMP dose-dependently increased all three inhibin subunit gene transcripts with maximal responses seen at 150 μM (α-subunit mRNA 2.3-fold, βA-subunit mRNA 1.8-fold and βB-subunit mRNA 2.8-fold over control). GnRH (100 nM) significantly increased inhibin α and βB-subunit mRNA levels 2.9-fold and 2.0-fold, respectively (P<0.01), but not βA-subunit mRNA. Collectively, the present findings demonstrate that in human term placental cells, gene expression of all inhibin subunits is under the direct influence of cAMP and further support a modulatory role of local GnRH in placental trophoblasts during late pregnancy.

The energetics of mercury adsorption on Cu(100)

AbstractWe have investigated the adsorption of mercury overlayers on Cu(100) by atom beam scattering, low energy electron diffraction and angle resolved photoemission. From our data we have calculated the isosteric heats in the adsorbed Hg layer on Cu(100) and compared these with results obtained for mercury on Fe(100), W(100) and Ni(100). We observe changes in the isosteric heat of adsorption that can be associated with the ordering of a c(2 × 2) Hg overlayer phase and the transition from a c(2 × 2) overlayer to a c(4 × 4) overlayer. The isosteric heat of adsorption is 0.50 ± 0.07 eV/atom (48 ± 7 kJ/mol) at zero coverage and reaches a maximum of 0.73 ± 0.04 eV/atom (70 ± 4 kJ/mol). From a combination of ABS and LEED, the structures of the two equilibrium ordered phases of Hg on Cu(100) have been identified, as well as the structures of several non-equilibrium phases.

Standard for object-oriented developmentObject-oriented metrics that predict maintainability

AbstractSoftware metrics have been studied in the procedural paradigm as a quantitative means of assessing the software development process as well as the quality of software products. Several studies have validated that various metrics are useful indicators of maintenance effort in the procedural paradigm. However, software metrics have rarely been studied in the object-oriented paradigm. Very few metrics have been proposed to measure object-oriented systems, and the proposed ones have not been validated. This research concentrates on several object-oriented software metrics and the validation of these metrics with maintenance effort in two commercial systems. Statistical analyses of a prediction model incorporating 10 metrics were performed. In addition, a more compact model with fewer metrics is presented.

Image codingMorphological segmentation applied to displaced frame difference coding

AbstractThis paper describes a segmentation algorithm based on morphological operators, which is applied to code the motion compensated prediction error images or the displaced frame differences (DFD). The DFDs result from various motion compensation techniques, e.g., block matching and pel-recursive techniques. Due to the low correlation in a DFD image, a segmentation based coding is more efficient than a transform based coding. The proposed method segments the DFDs using morphological operations. Various morphological operators are applied to eliminate isolated points and small regions of high energy and merge the small inner low-energy region to its neighboring high-energy region, resulting in a final image with a relatively small number of regions. Contours and regions are coded separately using entropy coding techniques. High compression ratios around 80:1 are achieved on DFDs with very good visual quality for the reconstructed sequences.

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