Showing papers by "Sun Yat-sen University published in 1997"
TL;DR: In this article, the existence and uniqueness of PDIE with non-Lipschitzian force is derived for backward stochastic differential equation (BSDE) with jumps, and the convergence theorems of solutions to BSDE and PDIE are derived.
177 citations
TL;DR: Amorphous and crystalline nano-Al 2 O 3 powders were prepared by direct oxidation and hydrolysis of pure aluminum, respectively The results by XRD and DTA measurements revealed that after annealing at 1370 K, the evolution in the amorphous nano-A 2 o 3 powder involved a low temperature relaxation followed by a simple γ- to α-Al O 3 transition.
153 citations
TL;DR: Four new complexes L2RuL'2+, where L = 2,2'-bipyridine (bpy) and 1,10-phenanthroline (phen), L' are Schiff bases or phenylhydrazones derived from 4,5-diazafluoren-9-one (AFO), were prepared and binding of these complexes to calf thymus DNA was investigated by absorption, circular dichroism spectroscopy, and viscosity measurement.
141 citations
Journal Article•
TL;DR: DPD activity was determined in 50 pairs of tumor and uninvolved liver specimens in Chinese cancer patients with hepatocellular carcinoma and hepatomas were found to have relatively high DPD activity, providing an explanation for the relative 5-fluorouracil resistance of hepatoma.
Abstract: Dihydropyrimidine dehydrogenase (DPD) is the initial, rate-limiting enzyme in the catabolism of 5-fluorouracil, one of the most widely used cancer chemotherapeutic agents. Previous studies have demonstrated the clinical importance of determination of DPD in cancer patients, suggesting that the efficacy and toxicity of 5-fluorouracil may directly relate to the DPD activity in both tumor and host tissues. In the present study, DPD activity was determined in 50 pairs of tumor and uninvolved liver specimens in Chinese cancer patients with hepatocellular carcinoma. Mean enzyme activity in uninvolved liver tissues (0.45 +/- 0.02 nmol/min/mg protein) was significantly higher than that in tumor specimens (0.34 +/- 0.03 nmol/min/mg protein). Statistical analysis revealed no significant differences in DPD activity of tumor and uninvolved liver specimens among different age and gender groups. Compared to previously reported tumor studies, hepatomas were found to have relatively high DPD activity. Since high levels of DPD would be expected to metabolize 5-fluorouracil, these findings may provide an explanation for the relative 5-fluorouracil resistance of hepatoma and may have implications for designing a new therapeutic strategy such as modulation of 5-fluorouracil chemotherapy by DPD inhibitors.
114 citations
TL;DR: In this paper, the authors conducted field work in a 300-hectare natural mangrove intertidal wetlands in Shenzhen, a newly developed city in southern China, to study the feasibility of using mangroves as a sewage treatment facility.
Abstract: Field work has been conducted in a 300-hectare natural mangrove intertidal wetlands in Shenzhen, a newly developed city in southern China, to study the feasibility of using mangrove wetlands as a sewage treatment facility. The present paper reports the results obtained in the recent year, between December 1994 and December 1995. Two parallel elongated sites (Sites A & B, each 180 m × 10 m) extending from land to sea were chosen for study. Since September 1991, Site A has received settled municipal sewage three times a week during the low ebb tide period when sediments at landward regions were dry. The hydraulic loading was 20 m3 per discharge and wastewater was soaked into the sediments within 50 m of the discharge points before the next incoming tide. Site B served as a control. Over the past months in 1994 and 1995, surface sediments and plant leaves were collected at identified locations in two sites at every six month intervals. The impact of sewage on mangrove plant growth was assessed by monitoring plant height, diameter and number of trees using the fixed plot technique.
104 citations
TL;DR: Preliminary data indicate that ondansetron, a selective 5-HT3 receptor antagonist, might serve as a prototype molecule for development of a novel series of local anesthetics.
Abstract: The purpose of this study was to determine whether ondansetron (OND) has local anesthetic effects.Using a patch-clamp technique, we showed that OND concentration dependently blocked Na channel currents in freshly isolated neurons of rat brains with a 50% inhibition concentration of 12 micro M. The b
103 citations
TL;DR: In this article, the effects of different electron donor and acceptor groups on the 1 H NMR, electronic absorption and emission spectra were studied, and it was shown that the addition of calf thymus DNA into the complex solution results in increases for both emissive intensities and excited state lifetimes, and indicates that the electron group on L has no significant effect on the intercalation binding mode between DNA and the complexes.
94 citations
TL;DR: In this article, chemical compositional data of respirable suspended particulate (RSP) measured at 11 stations of the Hong Kong Air Quality Monitoring Network between 1990 and 1994 were analyzed for their seasonal and spatial variations.
94 citations
TL;DR: In this paper, the copolymerization of styrene and ethylene has been performed using a titanocene-based catalytic system of cyclopentadienyltitanium triphenoxide (CpTi(OPh)3) and methylaluminoxane (MAO), which exhibited a high catalytic activity of 104−105 g (mof Ti·h)-1 and was found to selectively (more than 90 wt %) give an elastoplastic and amorphous styrene−ethylene (S−E) copoly
Abstract: The copolymerization of styrene and ethylene has been performed using a titanocene-based catalytic system of cyclopentadienyltitanium triphenoxide (CpTi(OPh)3) and methylaluminoxane (MAO). The catalyst system exhibited a high catalytic activity of 104−105 g (mof Ti·h)-1 and was found to selectively (more than 90 wt %) give an elastoplastic and amorphous styrene−ethylene (S−E) copolymer with a well-defined random/alternating microstructure and a single glass transition (Tg) as thoroughly characterized by solvent fractionation, GPC, 13C NMR, DSC, and WAXD. Under the reaction conditions employed, up to 54.5 mol % of styrene could be introduced into the copolymer chains. The composition, microstructure, molecular weight of the copolymers, and catalytic activity of the copolymerization are strongly dependent upon the comonomer feed ratio, polymerization temperature (Tp), CpTi(OPh)3/MAO mole ratio, and trimethylaluminum (TMA) content or structure in MAO. For 300 ⩽ Al/Ti < 1000, the copolymerization product was ...
92 citations
TL;DR: A series of Mg-ZSM-5 zeolite catalysts with different content of magnesium were prepared via a solid-state reaction of HZSM with magnesium chloride at 327°C as mentioned in this paper.
Abstract: A series of Mg-ZSM-5 zeolite catalysts with different content of magnesium were prepared via a solid-state reaction of HZSM-5 with magnesium chloride at 327°C. X-ray determinations demonstrated that the structure and crystallinity of the catalysts were not changed as compared with HZSM-5 zeolite. The acidity of the catalysts was characterized by temperature programmed desorption of ammonia and infrared spectra of pyridine adsorption. The studies indicated that their Bronsted acid sites decreased and Lewis acid sites slightly increased with increasing magnesium amount in the zeolites. The catalytic properties of the catalysts have been examined by choosing the alkylation of toluene with methanol as probe reaction. The results showed that the modified zeolite catalysts significantly improved the initial activity and lifetime. Para -selectivity also increases to a level of 80–90%. These results indicate that the solid-state reaction is an effective and convenient route for modification of the zeolite.
81 citations
TL;DR: Wavelet Petrov–Galerkin schemes based on discontinuous orthogonal multiwavelets are studied and it is proved that the condition number of the coefficient matrix for the linear system obtained from the wavelet petrov– Galerkin scheme is bounded.
Abstract: This paper continues the theme of the recent work [Z. Chen and Y. Xu, The Petrov–Galerkin and iterated Petrov–Galerkin methods for second kind integral equations, SIAM J. Numer. Anal., to appear] and further develops the Petrov–Galerkin method for Fredholm integral equations of the second kind. Specifically, we study wavelet Petrov–Galerkin schemes based on discontinuous orthogonal multiwavelets and prove that the condition number of the coefficient matrix for the linear system obtained from the wavelet Petrov–Galerkin scheme is bounded. In addition, we propose a truncation strategy which forms a basis for fast wavelet algorithms and analyze the order of convergence and computational complexity of these algorithms.
TL;DR: In this article, the nanostructure of nanowders is divided into a crystalline component and a disordered component, and the results show that the particles can be divided into disordered and orthorhombic SnO 2 phases.
TL;DR: In this article, the authors investigated the relationship between the wear debris morphology and the wear behavior of the bulk material and found that the fractal dimension of the worn debris was closely related to the wear behaviour of PEEK, and can be regarded as a measure of wear rate.
TL;DR: A new bis-indole, caulersin (4), was isolated from the alga Caulerpa serrulata, collected from the Xisha Islands in the South China Sea as mentioned in this paper.
Abstract: A new bis-indole, caulersin (4), was isolated from the alga Caulerpa serrulata, collected from the Xisha Islands in the South China Sea The structure was established by spectroscopic methods
TL;DR: In this article, the authors determined the structure and dissolution resistance of the CaO-ZrO 2 -TiO 2 and AlO 2 O 3 O 3 -AlO 3 O 4, AlO 4, BO 4 and Zr O 2, with Zr being the most dissolution resistant component.
Abstract: The purpose of this study is to determine the structure and dissolution resistance of the CaO–ZrO 2 –TiO 2 –Al 2 O 3 –B 2 O 3 –SiO 2 glass fabricated in Part (I). Vibrational spectroscopy indicated the structure units of the glass are SiO 4 , TiO 4 , BO 4 and their groupings for thermal exposure up to 750°C. The surface of an etched sample contained amorphous-phase-separated droplets which developed in multiple stages and clustered upon heating near the glass transition temperature, T g (ca. 640°C). Room temperature (30±1°C) dissolution of glass powders in aqueous solutions (pH=0, 1, 3, 5, 10 and 12) showed size-dependent leaching of cations Ca, Al, Ti and Zr, with Zr the most dissolution-resistant component. The leaching of the cations Ca and Al was linear with time in the initial dissolution stage and each had a logarithmic dissolution rate versus pH dependence; the slope being negative in acidic while positive in basic condition with a minimum dissolution rate in the pH range of 6.5 to 8.5. Dissolution of a partially devitrified glass slab under acidic (pH=0) or basic (pH=12) conditions indicated that glass/crystal (ZrO 2 derived) interfaces were preferentially dissolved with the crystals being more resistant. An Al-depleted layer and ridge-free hillocks developed on the glass surface at pH=12 and 0, respectively.
TL;DR: It is suggested that white sturgeon subyearlings can utilize diets with high lipid contents to display good growth without major adverse effects on body composition and liver lipogenic enzyme activities.
Abstract: Four diets formulated for salmon were fed to 0.11 kg white sturgeon, Acipenser transmontanus Richardson, for 8 weeks. Dietary compositions ranged from 258 to 402 g lipid kg−1, 535–378 g protein kg−1 and 22.7–14.4 g protein MJ−1 gross energy.
Fish in all treatments grew rapidly, utilized the diets efficiently and had body compositions similar to what has been found in previous studies, but there were some dietary effects. Sturgeon fed the diet with the highest lipid content and lowest protein/energy ratio had lower (P < 0.05) specific growth rate, feed efficiency, and liver moisture and protein contents, and 6-phosphogluconate dehydrogenase activity, but higher liver lipid contents than fish fed the other three diets. Condition factor, organ to body weight ratios, whole-body and plasma concentrations of protein, glucose and triglyceride, and liver glucose-6-phosphate dehydrogenase, isocitrate dehydrogenase and malic enzyme activities did not differ significantly among dietary treatments. This suggests that white sturgeon subyearlings can utilize diets with high lipid contents (258–357 g kg−1) to display good growth without major adverse effects on body composition and liver lipogenic enzyme activities.
TL;DR: Although seedling growth suffered from the adverse environment of Pb/Zn tailings, they became established on tailings stands, in the greenhouse, as well as on the actual tailings dam, and completed their life cycle in 4 months.
Abstract: in pure and amended Pb/Zn tailings. About 90% of seeds of S. rostrata germinated in pure Pb/Zn tailings, which contained high concentrations of Pb, Zn, Cu, and Cd. Although seedling growth suffered from the adverse environment of Pb/Zn tailings, they became established on tailings stands, in the greenhouse, as well as on the actual tailings dam, and completed their life cycle in 4 months. Dry matter production and nitrogen accumulation was 3200 kg/ha and 69.4 kg/ha, respectively in the actual tailings dam. Applying inorganic fertilizer to Pb/Zn tailings led to no obvious improvement in growth and nodulation of S. rostrata, while tailings amended by river sediment or domestic refuse rich in organic matter improved the growth and nodulation of the species. Azorhizobium caulinodans survived and formed N-fixing stem and root nodules in S. rostrata grown in pure Pb/Zn tailings with a nodule biomass exceeding 300 mg fresh matter per plant.
TL;DR: In this article, the phase separation in polycarbonate (PC) blends was controlled by varying the composition, and the PC-epoxy reaction, and utilizing curing agents of different reactivity.
TL;DR: In this paper, the thermal performance of the wear debris and the worn pin tops of polyetheretherketone (PEEK) after unlubricated sliding wear tests at a constant sliding speed of 1 m s −1.
TL;DR: In this paper, young plants of Aegiceras corniculatum, a dominant mangrove species, were collected from Futian Mangrove Swamp in Shenzhen, The People's Republic of China, and grown in simulated tide tanks containing manmarve sediments.
Abstract: Young plants of Aegiceras corniculatum, a dominant mangrove species, were collected from Futian Mangrove Swamp in Shenzhen, The People’s Republic of China, and grown in simulated tide tanks containing mangrove sediments. After acclimatisation in the greenhouse for 6 months, the plants were irrigated with either synthetic sewage of various strengths (NW, FW and TW) or artificial seawater (as control). NW had the characteristics and strength equivalent to municipal wastewater, while FW and TW contained 5 and 10 times the nutrient and heavy metal concentrations of the NW, respectively. Results showed that the young plants of A. corniculatum were able to tolerate the wastewater (TW) with highest concentration of nutrients and heavy metals after one year treatment. The growth of TW treated plants, measured in terms of stem height, basal diameter and biomass, was comparable to that found in the control. The plants treated with NW and FW had significantly greater growth than the control, indicating that the nutrients contained in sewage are beneficial to mangrove plants. Physiological parameters such as chlorophyll content, the ratio of chlorophyll a and b, proline concentration and root activity did not show any significant changes among plants treated with wastewater of various strengths and the control, suggesting that sewage addition did not cause any apparent physiological impact on growth of A. corniculatum. Nevertheless, the plants which received sewage with highest levels of heavy metals (TW treatment) appeared to have lower content of free water but higher amount of bound water than FW, NW and the control. Higher electric conductance was also found in plants treated with TW.
TL;DR: A tetranuclear terbium(III) complex has been synthesized and shown by X-ray crystallography to have a cubane-like Tb4(μ3-OH)4 (μ2-carboxylato-O,O′)6 core.
Posted Content•
TL;DR: In this paper, the determinants of investment in Czech industry during the period from 1993 through 1994, a period when the transition toward a market economy was rapidly gaining momentum, were investigated.
Abstract: We use enterprise data to study the determinants of investment in Czech industry during the period from 1993 through 1994, a period when the transition toward a market economy was rapidly gaining momentum. We investigate accelerator type models modified to include financial variables intended to reflect the possibility of credit rationing. Overall, we find that finance is an important determinant of investment for firms in a transition economy. In particular we find that de novo private firms and firms privatized early invested heavily during 1993 and that they were financially constrained in 1993 and even more so in 1994. In contrast, state owned enterprises including those that were privatized in the course of 1994 invested relatively little in 1993 and were less financially constrained in 1994 than in 1993. This evidence is consistent with a pattern that state owned enterprises were placed under financial discipline relatively early in the Czech transition and that their financial access improved with the approach of their privatization.
TL;DR: The 3 310m-high Chia-min Lake records the climatic history since 4 ka B P in Taiwan as discussed by the authors, and the warm/wet period before 22 ka BP seemed to correspond to the later part of the Holocene Megathermal, and the cold/dry period during 0-22 ka BP corresponded to the Katathermal.
Abstract: The 3 310-m-high Chia-min Lake records the climatic history since 4 ka B P in Taiwan The warm/wet period before 22 ka BP seemed to correspond to the later part of the Holocene Megathermal, and the cold/dry period during 0–22 ka B P corresponded to the Katathermal Before the termination of the Megathermal, an especially warm and humid segment (22–24 ka B P) emerged The paleoclimatic records from Yuen-yang and Chi-tsai Lakes support the notion that the Megathermal in Taiwan terminated during 2—23 ka B P A warm segment (820–1 320 AD) in the Katathermal could be considered the Medieval Warm Period The climate turned cold and dry after 1 320 AD and this indicated the onset of the Little Ice Age These paleoclimatic variations are also in good agreement with those recorded in Great Ghost Lake
TL;DR: In this paper, a dinuclear copper(II) complex has been prepared by reaction of tacd with Cu(MeCO 2 ) 2 -H 2 O in ethanolic solution, and the crystal structure shows that a pair of copper (II) atoms separated at 3.040(5)-2.144(4) A, Cu0 bonds at 1.895(2)-1.970(3) A.
TL;DR: It is confirmed that the benthic macrofauna within Mangroves is low in species diversity and high in population counts incomparison with a frontal mudflat and longitudinal zonation of the fauna from landward to seaward will also bediscussed.
Abstract: Benthic macrofauna and possible effects on community structureofdischarging municipal wastewater to Futian National MangroveReserve, the People‘s Republic of China, were investigated.Eighty-four species of ground-dwelling fauna belonging to 7Phyla,9 Classes, 46 Families and 65 Genera were identified. Abundantfamilies were Assimineidae, Melanidae, Potamididae,Ocypodidae,Grapsidae and Periophthalmidae. Between April 1991 to January1993,no obvious seasonal fluctuation in species compositionoccurred.Total biomass also remained unchanged. However, total densityshowed peaks in January and July (both in section A and B),probably due to the molluscs.A selected site of the mangroves was treated with municipalwastewater (60 m3 per week for 16 consecutive months). Incomparison to a control site, the effect of wastewaterdischarge ontotal mean biomass and density (particularly of molluscs andcrustaceans) appeared non-significant P?0.05). Thecommunity structure remained unchanged although some saprobicspecies emerged and total biomass in the area close to thewastewater front increased slightly. Multivariate analysisindicated that there probably was an initial inhibition periodanda subsequent recovery period for benthic fauna in response tothedischarged wastewater in the mangrove swamp.The study confirms that the benthic macrofauna withinmangroves islow in species diversity and high in population counts incomparison with a frontal mudflat. Longitudinal zonation ofthefauna from landward to seaward will also bediscussed.
TL;DR: The EtOAc extract of A. macrocephala was chromatographed to give a novel bisesquiterpenoid, biatractylolide, which was determined by spectroscopic methods, mainly 2D-NMR techniques.
Abstract: Atractylodes macrocephala Koidz is a traditional medicinal plant in China and is known for the treatment of gastroenteric and splenic disorders. The EtOAc extract of A. macrocephala was chromatographed to give a novel bisesquiterpenoid, biatractylolide (1). The structure of 1 was determined by spectroscopic methods, mainly 2D-NMR techniques.
TL;DR: Two polymeric cadmium(II) complexes of betaine (Me3N+CH2CO2− = bet, [Cd3(bet)4(H2O)2Cl4]n(ClO4)2n (1) and [Ccd( bet)2(NO3)]n(CO4n)n (2), have been prepared and characterized by X-ray single-crystal structural analysis.
TL;DR: The resistance of C. neoformans to the fungicidal effects of RNI and ROI is related to virulence, and it is suggested that the resistance to nitrogen‐ and oxygen‐derived oxidants may be one of the factors to determine the outcome of infection with C. Neoformans.
Abstract: We investigated the susceptibility of three clinically isolated strains of Cryptococcus neoformans with different virulences to reactive nitrogen and oxygen intermediates (RNI and ROI, respectively), representing two important mediators of macrophage microbicidal activity. All mice infected with the highly virulent strain of C. neoformans, YC-11, died within 3 to 6 weeks because of rapid multiplication of the organism in the lungs and dissemination to the brain. In contrast, a weakly virulent strain, YC-13, was almost completely eradicated from the lungs and did not disseminate to the brain, leading to survival of all infected animals during the period of observation (15 weeks). The virulence of the third strain, YC-5, was intermediate between the other two strains. To examine the susceptibility of C. neoformans to the fungicidal effect of nitric oxide (NO) and superoxide anions (O2-), the organisms were exposed to these oxidants, which were chemically generated in a cell-free system. Interestingly, the number of live YC-13 yeast cells was markedly reduced after exposure to NO and O2-. In contrast, YC-11 was almost completely resistant to the killing effect of these oxidants. YC-5 showed an intermediate susceptibility. Our results demonstrate that the resistance of C. neoformans to the fungicidal effects of RNI and ROI is related to virulence, and suggest that the resistance to nitrogen- and oxygen-derived oxidants may be one of the factors to determine the outcome of infection with C. neoformans.
TL;DR: In this paper, the results of EHMO calculations show that the PdO bonds are weaker than Pd ǫ s bonds in both compounds and large delocalized π bonds extend in the (mp)2Pd2S2 plane in 1 and in the pd(mpo)2S 2 plane in 2.
TL;DR: In this article, a homogeneous catalyst composed of (η 5 -cyclopentadienyl)tribenzyloxytitanium and methylaluminoxane (MAO) was used as a cocatalyst.
Abstract: Syndiotactic polystyrene was efficiently prepared in the presence of a homogeneous catalyst composed of (η 5 -cyclopentadienyl)tribenzyloxytitanium and methylaluminoxane (MAO) as a cocatalyst. Influences of various polymerization conditions, e.g., [Ti], [MAO], [St], temperature and the content of retained trimethylaluminium (TMA) in MAO on the catalytic activity, syndiotacticity and molecular weight of the polymer were studied. It was found that the retained TMA plays an important role in the polymerization. Lowering the retained TMA content in MAO decreases the activity of the catalyst remarkably. Addition of external alkylaluminium (TMA or triisobutylaluminium) into the catalyst system with MAO containing low amounts of retained TMA promotes styrene polymerization.