Showing papers by "Xiamen University published in 1995"
TL;DR: It is concluded that Victoria Harbour is more polluted than Xiamen Harbour, and the structure of the benthic community provides further evidence to support this claim.
280 citations
TL;DR: It was demonstrated that sediment elutriates obtained from site VS14 were of greatest toxicity, and significant correlations were found between the results of the algal toxicity test and the coliform count and metal content of the sediments.
66 citations
TL;DR: In this article, the electron detachment energies and fragmentation energies of CnN− anions were calculated based on ab initio calculations for the electron detach energies and the fragmentation energies.
53 citations
TL;DR: In this paper, the effect of cyclodextrin inclusion complex formation on the twisted intramolecular charge transfer (TICT) of the included compound was examined using the TICT-typical dual fluorescence for the p-dimethylaminobenzoic acid (DMABOA)-β-cyclodesxtrin (β-CD) system in buffered and unbuffered (pH 4.12 and 8.06) solutions.
Abstract: The effect of cyclodextrin inclusion complex formation on the twisted intramolecular charge transfer (TICT) of the included compound was examined using the TICT-typical dual fluorescence for the p-dimethylaminobenzoic acid (DMABOA)-β-cyclodextrin (β-CD) system in buffered (pH 4.12 and 8.00) and unbuffered (pH 5.06) solutions. The host-to-guest ratio of the DMABOA-β-CD inclusion complex is evaluated to be 1 : 1 in the three solutions from an analysis of the fluorescence intensity data by two methods. Enhanced LE (locally excited state) and TICT emissions and Ia/Ib ratio, a blue-shifted TICT fluorescence band and a stronger excitation wavelength dependence of the TICT fluorescence for DMABOA in the β-CD inclusion complex are observed. The correlation of the Ia/Ib ratio with the medium polarity is opposite in the inclusion complex to that observed in organic solvents. The TICT fluorescence of the DMABOA-β-CD inclusion complex with DMABOA in the basic form shows a stronger excitation wavelength dependence than that with DMABOA in the acidic form. A decreased pKa of DMABOA in the β-CD inclusion complex is determined. This is taken as evidence that the Me2N group of the DMABOA molecule in the β-CD cavity. TICT is shown to be viscosity dependent in the cyclodextrin inclusion complex. The dependence of the TICT fluorescence of DMABOA in the inclusion complex on the polarity, viscosity and excitation wavelength is discussed in detail with regard to the dynamic scheme of the TICT model and the structural characteristics of the ground and excited states.
52 citations
TL;DR: In this article, a planar four-member V2O2 ring with bridging hydroxyl oxygens was constructed for the reaction of citric acid and metavanadate in neutral solution.
50 citations
TL;DR: In this article, the electrooxidation of glassy carbon electrodes in acid and neutral solution has been investigated using in situ FTIR spectroelectrochemical techniques, and the formation and transformation of intermediate oxide species in different potential regions has been observed.
Abstract: The electrooxidation of glassy carbon electrodes in acid and neutral solution has been investigated using in situ FTIR spectroelectrochemical techniques. The formation and transformation of intermediate oxide species in different potential regions has been observed. The results show that in the lower anodic potential region (i.e., + 1.65 V vs SCE), the electrooxidation of carbon is a combination of electrochemical and chemical oxidation. A more detailed electrooxidation mechanism is proposed based on the experimental results.
50 citations
TL;DR: In this paper, the number of total valence electrons of the cluster anions was derived from their electronic features, and a qualitative molecular orbital diagram was drawn to relate the total number of valence electron counts of the anions to their electronic properties.
48 citations
TL;DR: In situ Raman spectroscopy has been employed to investigate oxygen adsorption on electrolytic silver catalyst under industrial conditions for methanol oxidation to formaldehyde as discussed by the authors, and both adsorbed atomic and molecular oxygen species are shown to exist on the silver surface in O2 flow above 870 K.
Abstract: In situ Raman spectroscopy has been employed to investigate oxygen adsorption on electrolytic silver catalyst under industrial conditions for methanol oxidation to formaldehyde. Both adsorbed atomic and molecular oxygen species are shown to exist on the silver surface in O2 flow above 870 K. The peroxide species is determined to be a precursor to atomic adsorbed oxygen. In consideration of the industrial process, the molecular mechanism of the partial oxidation of methanol and the adsorption mechanism of oxygen on electrolytic silver surface are discussed.
40 citations
TL;DR: In this paper, an absorption-refrigeration system affected by the irreversibility of finite-rate heat transfer is modelled as a combined cycle, which consists of an endoreversible heat engine and an endorversible refrigerator, and the primary performance parameters such as the coefficient of performance, specific cooling load, heat transfer areas of heat exchangers, temperatures of the working fluid in heat exchanger, and rate of entropy production are optimized.
38 citations
TL;DR: In this article, a series of cluster anions C n X− are produced from laser ablation of appropriate samples, where X is selected as a group-VB element, and the recorded mass spectra of these clusters display a drastic even/odd alternation on ion intensities.
Abstract: A series of cluster anions C n X− are produced from laser ablation of appropriate samples, where X is selected as a group-VB element. The recorded mass spectra of these cluster anions display a drastic even/odd alternation on ion intensities: For C n N−, only anions with oddn can be observed; For C n P− and C n As−, cluster anions with evenn are produced but with lower signal intensities; For C n Sb−, the signal intensity of clusters does not show even/odd alternation; Finally, for C n Bi−, the intensities of cluster anions with evenn are higher than those with oddn. This parity effect can be attributed to the linear structure of the cluster anions, and the parity reversal of C n X− from C n N− to C n Bi− can be explained from the electronegativity decreasing of the heteroatom X as it descends in the group. The Huckel model was applied to account the structural feature of these clusters.
37 citations
TL;DR: Using a special holographic technique, moiré patterns can be recorded with a horizontal parallax, thus producing a fascinating artistic effect and being used as secret codes in security holograms for different security purposes.
Abstract: Using a special holographic technique, moire patterns can be recorded with a horizontal parallax, thus producing a fascinating artistic effect. With special characteristics, holographic moire patterns can be used as secret codes in security holograms for different security purposes. A remarkable anticounterfeit effect has been achieved by using this kind of security hologram to protect famous high-quality products. The technique used for recording moire patterns is described, and sample holograms are shown.
TL;DR: In this paper, the optimal performance of an absorption heat transformer was investigated by using the cyclic model with continuous flow, and the effect of thermal resistances between the heat transformer and the heat reservoirs was considered in the model.
Abstract: The optimal performance of an absorption heat transformer, i.e. a type II absorption heat pump, is investigated by using the cyclic model with continuous flow. The effect of thermal resistances between the heat transformer and the heat reservoirs is considered in the model. A general expression related to the rate of heat-pumping, the coefficient of performance and the overall heat transfer area of the heat transformer is derived. The expression is used to optimise the main performance parameters of the heat transformer. The maximum rate of heat-pumping and the corresponding coefficient of performance are calculated. For a given overall heat transfer area of the heat transformer, the optimal relation of the heat transfer areas of the heat exchangers is obtained. The problems concerning the optimal choices of other performance parameters are discussed. The results obtained here can not only enrich the theory of finite time thermodynamics, but also provide some new theoretical bases for the optimal design and operation of real absorption heat transformers.
TL;DR: The structural changes as a function of OH concentration in the blend system of poly(n-butyl methacrylate) (PBMA) and hydroxyl-modified polystyrene (PS(OH)) are investigated by a non-radiative energy transfer technique and viscometry.
TL;DR: In this article, the bonding nature and structural configuration of binary anions of aluminium with some non-metallic elements, including oxygen, sulfur, phosphorus, arsenic and carbon, were recorded by mass spectrometry.
TL;DR: Vanadate1 and vanadate2 have been characterized by X-ray structure analyses as discussed by the authors, and they have been obtained in the monoclinic space groupP21/n (No. 14) with unit cell parameters:a=9.304(2),b=11.756(2)A,c= 11.988(3)av (hydroxy) and 1.974(3)-A(α-carboxyl), andDc=1.72°.
Abstract: Potassium and ammonium dimeric (citrato)dioxovanadium(V) hydrate K2[VO2(H2cit)]2·4H2O1 and (NH4)2[VO2(H2cit)]2·2H2O2 (H4cit=citric acid) have been prepared and characterized by X-ray structure analyses. Vanadate1 crystallizes in the monoclinic space groupP21/n (No. 14) with unit cell parameters:a=9.304(2),b=11.756(2),c=11.911(2)A, β=111.72(3)°, andD
c=1.911 g/cm3,Z=2; Vanadate2 also crystallizes in the monoclinic space groupP21/n with unit cell parameters:a=9.719(2),b=11.111(3),c=11.294(2)A, β=109.03(2)°, andD
c=1.781 g/cm3,Z=2. Each dimer contains a centro-symmetric planar four-member V2O2 ring with two exocyclic citrate entities coordinated by the oxygen atoms of the hydroxy-and α-carboxylate ligands, while the other two β-carboxylate groups remain uncomplexed. Principal dimensions of the V−O bonds are 1.986(4)av (hydroxy) and 1.980(3)A(α-carboxyl) for vanadate1, 1.988(2)av (hydroxy) and 1.974(3)A(α-carboxyl) for vanadate2.
TL;DR: In this paper, the authors discuss some properties of a quadratic matrix equation with some restrictions, then use these results on the algebraic Riccati equation to get a new algorithm.
TL;DR: In this article, a home-made tandem time-of-flight mass spectrometer was used to study the structural unit of the phosphorus clusters and the number of tetramer fragments ejected upon dissociation increases with the parent phosphorus cluster size.
TL;DR: In this article, the authors investigated the performance of BaF2 LaOF and lattice-contracted LaOF catalysts for the catalytic conversion of ethane to ethylene, and they found that the result was similar to the results obtained in this paper.
Abstract: The oxidative dehydrogenation of ethane was investigated on LaOF and BaF2 LaOF catalysts. It was found that BaF2 LaOF was more effective than LaOF for the catalytic conversion of ethane to ethylene. A selectivity of 74% for ethylene was obtained at 55% ethane conversion over 8mol-%BaF2 LaOF compared with a selectivity of 58.5% for ethylene at 44.6% ethane conversion over LaOF under the same conditions: reaction temperature 660°C, C2H6:O2=67.7:32.3 and a feed gas flow-rate of 90 ml/min. It was also found that part of the ethylene in the products was produced by the thermal cracking of ethane. X-ray diffraction results showed that, when the molar percentage of BaF2 in BaF2 LaOF was less than 18%, only tetragonal LaOF was observed, and when the molar percent of BaF2 in BaF2 LaOF increased from 18% to 50%, tetragonal LaOF and lattice-contracted BaF2 were observed.
TL;DR: In this paper, suspended particles collected in January 1991 in the Solo River system and in the Serayu River, Java, Indonesia were analyzed by GC and GC/MS, after derivatization into their trimethylsilyl esters, by extracting free sterols from particles larger than 0.7 μm.
Abstract: Sterols were analyzed in suspended particles collected in January 1991 in the Solo River system and in the Serayu River, Java, Indonesia. Free sterols were extracted from particles larger than 0.7 μm and analyzed, after derivatization into their trimethylsilyl esters, by GC and GC/MS. Concentrations of total sterols ranged from 438 to 7922 ng/1, or from 2.4 to 183.8 ng/mg of total suspended matter, which varied from 3.3 to 400 and 471 mg/l, respectively in the Serayu River and at the downstream station in the Solo River. POC concentrations also varied in a wide range, from 0.91 to 4.72 and 6.13% of TSM, respectively at the above stations, and were associated with sterol/POC values ranging from 0.15 to 1.75 μg/mg. Eleven structures of C27, C28 and C29 sterols and associated stanols were identified. 28Δ3,22 was only found at downstream stations in the Solo River and in the Serayu River. This unique distribution, different from that of other C27, C28 and C29 sterols, suggests a predominantly autochthonous origin for these compounds associated with an increased planktonic biosynthesis near the estuary. Concentrations of 28Δ5, 29Δ5,22 and 29Δ5 showed similar spatial distributions and increased downstream, reflecting the significant accumulation of organic matter originating from the vegetation of the various drainage basins. Values of the autochthonous versus terrigenous sterol index, defined as 27Δ5/29Δ5,22 + 29Δ5 were in the 1.4–1.9 range at upstream stations, whereas at downstream stations lower values were found, 0.4–0.6, which also corresponded to higher concentrations of TSM and lower POC values. Insofar as the stanol/stenol values can be used to estimate the bacterial activity of oxic waters, simultaneous variations of C27, and C29 stenol/stanol pairs suggest rather different bacterial degradation capacities of autochthonous versus allochthonous organic matter. The wide differencies between the values of the stenol/stanol pairs observed in one of the main tributaries and in downstream stations of the Solo River is evidence that allochthonous organic matter is much more resistant than autochthonous matter. The low index value observed in the Serayu River indicates the highly refractory nature of both autochthonous and allochthonous organic material.
TL;DR: Wang et al. as mentioned in this paper collected over 100 hair samples from the Xiamen area of south China, including 72 healthy people and 34 cancer patients, for the study of distinguishing cancer patients from others; another 64 hair samples were collected from patients with liver, stomach, lung, and miscellaneous cancers and were used for the discrimination analysis of different types of cancers.
TL;DR: In this article, the robust stability problems of linear discrete-time systems with structured perturbations are considered and the necessary and sufficient condition of interval stability is given and the maximal bound of robust stability is presented for systems with a non-negative or non-positive nominal system matrix.
Abstract: The robust stability problems of linear discrete-time systems with structured perturbations are considered. The necessary and sufficient condition of interval stability is given and the maximal bound of robust stability is presented for systems with a non-negative or non-positive nominal system matrix. Further, it is shown that the given necessary and sufficient condition and the given maximal robust bound are still valid for time-varying perturbations and nonlinear perturbations.
TL;DR: In this paper, the oxidative coupling of methane (OCM) was studied on BaF 2 LaOF and good catalytic results were obtained under the conditions of GHSV = 15 000 h−1 and a reaction temperature of 1043 K, a C2 yield of 20.66% with a CH4 conversion of 33.08% and a C 2 selectivity of 62.47% was achieved at CH4:O2 = 3:1.
Abstract: The oxidative coupling of methane (OCM) was studied on BaF 2 LaOF and good catalytic results were obtained. Under the conditions of GHSV = 15 000 h−1 and a reaction temperature of 1043 K, a C2 yield of 20.66% with a CH4 conversion of 33.08% and a C2 selectivity of 62.47% was achieved at CH4:O2 = 3:1, and high C2 selectivities of 81.20% and 84.55% with a CH4 conversion of 19.53% and 16.54% were obtained at CH4:O2 ratios of 6:1 and 9:1, respectively. X-ray diffraction results showed that only tetragonal LaOF existed in the BaF 2 LaOF catalysts with BaF2 content below 18 mol-%, but a contracted BaF2 phase was also observed at higher BaF2 content (above 18 mol-%).
TL;DR: In this paper, the inverse muon polarization in the three-Higgs model with scalar and pseudo scalar four-Fermi interactions is calculated and a possible constraint on parameters is obtained assuming sensitivity of the up-coming KEK experiment.
Abstract: Transverse muon polarization in the $K^+ \rightarrow \mu^+
u \gamma$ decay is calculated in the model with scalar and pseudo scalar four-Fermi interactions. Combined with a similar calculation in the $K^+ \rightarrow \mu^+
u \pi^0$ decay, a possible constraint on parameters in the three-Higgs model is obtained assuming sensitivity of the up-coming KEK experiment. It is pointed out that the predictions for the two polarizations are strongly correlated in the three Higgs model.
TL;DR: In this paper, a class of methods for computing including estimates for the range of a polynomial over an interval is defined, and two special cases of the Bernstein form and the B-spline form are shown to be members of the class.
TL;DR: In this article, the authors investigated the kinetics of dissociative adsorption of formaldehyde on Pt(111) electrodes using a programmed potential step technique and in situ time-resolved Fourier transform IR spectroscopy (TR-FTIRS).
TL;DR: In this article, the surface-enhanced Raman scattering (SERS) of water molecules from gold electrodes is reported for the first time and the metal substrate effect on the SERS active water is investigated by comparison of gold with silver in 3 M KCl.
TL;DR: The results of in situ IR characterization of the surface oxygen species at 650°C suggested that O 2 − might be the active oxygen adspecies for the oxidative coupling of methane reaction.
Abstract: The catalytic performance evaluation results showed that the CH 4 conversion, C 2 selectivity and ethylene to ethane ratio were significantly higher over LaF 3 /SrO and SrF 2 /La 2 O 3 than those over SrO/La 2 O 3 and the maximum C 2 yields of 18–20% were achieved over the LaF 3 /SrO and SrF 2 /La 2 O 3 catalysts at 650–750°C. XRD analysis of the fresh catalysts indicated that, with the addition of LaF 3 to SrO and treatment in air at high temperature, anionic and/or cationic exchange between oxides and fluorides lattices took place to some extent, leading to the formation of SrF 2 and LaOF. The UV spectra of pyridine adsorption and the temperature-programmed desorption spectra of CO 2 adsorption on SrF 2 /La 2 O 3 and SrO/La 2 O 3 showed that surface of the catalyst containing fluoride was more acidic and less basic than that of the corresponding oxide system. The XPS characterizations of O 2 -adsorbed catalysts revealed that the catalysts containing F − were more conducive to the formation of the oxygen species with fewer negative charges. The results of in situ IR characterization of the surface oxygen species at 650°C suggested that O 2 − might be the active oxygen adspecies for the oxidative coupling of methane reaction.
TL;DR: In this article, the optimal performance of a two-stage endoreversible combined cycle is investigated for steady-state operation, where the cycle efficiency at maximum specific power output equals the Curzon-Ahlborn efficiency.
TL;DR: In this article, the geometry around the Sb(III) ion in both chelates can be described as a distorted ψ-pentagonal bipyramid with a lone electron pair at the axial position.
TL;DR: In this paper, the bonding of CO to the NiO(100) surface has been investigated by means of the DV-Xα method, and it was shown that the interaction between CO and NiO is mainly electrostatic.