Showing papers by "Sichuan University published in 1998"
TL;DR: It is proved that the maximum safe harvest may be far less than what would be assumed from a local analysis for the equilibria and that the harvested predator-prey system may exhibit very complicated dynamics such as a spontaneous appearance of a homoclinic orbit and multiple limit cycles.
Abstract: The study of populational dynamics with harvesting is related to the optimal man- agement of renewable resources. In this paper we consider a predator-prey model in which two ecologically interacting species are harvested independently with constant rates. The main purpose of the present work is to offer a complete mathematical analysis for the model and to describe some of the significant qualitative results that may be expected to arise from the interplay of biological forces. Our study shows that the maximum safe harvest may be far less than what would be assumed from a local analysis for the equilibria. It is also proved that the harvested predator-prey system may exhibit very complicated dynamics such as a spontaneous appearance of a homoclinic orbit and multiple limit cycles.
175 citations
TL;DR: In this paper, a new class of variational inclusions with non-compact valued mappings is introduced and a new iterative algorithm is proposed. But this algorithm is not a completely general class of inclusions.
Abstract: In this paper, we introduce and study a new completely general class of variational inclusions with noncompact valued mappings and construct some new iterative algorithms. We prove the existence of solutions for the completely general class of variational inclusions and the convergence of iterative sequences generated by the algorithms.
108 citations
TL;DR: At one year postoperation, the implant was completely fused with natural bone on the interfaces between them, new bone had grown into most of the porous structures of the implants, and a natural bone tissue layer formed on the inside surface of the artificial vertebral lamina.
100 citations
TL;DR: In this paper, the authors prove new convergence theorems of the Ishikawa and Mann iteration sequences for strongly accretive and strongly pseudo-contractive mappings by using the new inequality and the new approximation methods.
98 citations
TL;DR: In this article, a new class of generalized nonlinear implicit quasi-variational inclusions was introduced and proved its equivalence with a class of fixed point problems by making use of the properties of maximal monotone.
Abstract: In this paper, we introduce a new class of generalized nonlinear implicit quasi-variational inclusions and prove its equivalence with a class of fixed point problems by making use of the properties of maximal monotone. We also prove the existence of solutions for this generalized nonlinear implicit quasi-variational inclusions and the convergence of iterative sequences generated by the perturbed algorithms.
78 citations
TL;DR: In this paper, the electrocaloric effect of (1−−x)Pb(Mg1/3Nb2/3)O3-PbTiO3 [abbreviated as PMN-xPT] ferroelectric ceramics with x being 0.08, 0.10, and 0.25, respectively, were measured near room temperature, and the origins of the electro-caloric effects of these cerams were discussed.
68 citations
TL;DR: It was found that amorphous components were transformed completely into crystalline HA after heating at 490 degrees C with a partial water vapor pressure of 0.01 MPa for 2 h and degradation in vitro showed that Dmax3 was more stable than Dmax1 and Dmax2.
Abstract: Study of an amorphous phase in plasma-sprayed hydroxyapatite (HA) coatings is important owing to its unique characteristics and nonnegligible amount of the amorphous phase compared to crystalline HA. However, little is known about the component parts of an amorphous phase. It is known that amorphous phase usually appears as the diffusion maximum (Dmax) in X-ray diffraction (XRD) patterns. Analyzing Dmax, including the position (Pmax) and area of Dmax, we can indicate the component parts of an amorphous phase and their transitions. In this study, the variation of Dmax in XRD patterns of the coatings during plasma spraying, in postheating, and in dissolving in vitro was studied with the aid of XRD. It was found that component parts of the amorphous phase in the coating varied with increasing thickness, consisting of two parts represented by Dmax1, located between 29.4 and 29.8 degrees (2θ), and Dmax2, located between 31.0 and 31.4 degrees (2θ). It was concluded that Dmax3, located between 32.0 and 32.4 degrees (2θ), should be referred to as nanocrystals of HA. In addition, the particle size of the starting powder may affect the component parts of the amorphous phase in the coating in addition to thickness. With vacuum heating (650°C) and water vapor treatment at a low temperature (125°C) in a saturated vaporic atmosphere, transition of the amorphous components was not as efficient as that at 490°C with water vapor. The reason might be that the amorphous-to-crystalline HA conversion is dependent on both temperature and water vapor pressure. It was found that amorphous components were transformed completely into crystalline HA after heating at 490°C with a partial water vapor pressure of 0.01 MPa for 2 h. It was concluded that the unstable amorphous components (Dmax1, Dmax2) converted into more stable nanocrystals of HA (Dmax3). Degradation in vitro showed that Dmax3 was more stable than Dmax1 and Dmax2. It was concluded that nucleation of apatite in vitro should be attributed to nanocrystals of HA (Dmax3) except for the amorphous components. It is recommended that the optimal phasic contents of the plasma-sprayed HA coating be mainly composed of crystalline HA and nanocrystals of HA (Dmax3) in terms of the stability and biocompatibility of the coating. © 1998 John Wiley & Sons, Inc. J Biomed Mater Res, 40, 407–413, 1998.
40 citations
TL;DR: In this paper, it was found that the excess amount of MgO and PbO and the sintering temperature have great effect on the crystallographic properties of the ceramics.
Abstract: Lead magnesium niobate Pb(Mg1/3Nb2/3)O3 — lead titanate PbTiO3 [abbr. as (1 — x) PMN — x PT] ferroelectric ceramics with different excesses of MgO and PbO were systematically studied under different processing conditions for ferroelectric refrigeration application. It was found that the excess amount of MgO and PbO, and the sintering temperature have great effect on the crystallographic properties of the ceramics. In our experiments, (1 — x) PMN —x PT (x = 0.08, x = 0.10, and x = 0.25 respectively) with the excesses of 2 mol% MgO and 2 mol% PbO ceramics sintered at 1250 °C/1 hour possess the desired perovskite structures and large electrocaloric temperature change (ΔT = 1 K and more) in the vicinity of room temperature under a dc electric field of 1.5 kV/mm. It is expected that (1 — x) PMN — x PT electrocaloric ceramics could be applied for cascade refrigeration near room temperature.
38 citations
TL;DR: Differences between the two implants, mainly the difference in crystallinity of the HA coating (62 vs. 40%), have no significant influence on bone bonding ability, bone bonding strength, tensile failure mode, and degradation of the coating.
Abstract: Tensile strength testing of the interface between bone and a plasma-sprayed hydroxyapatite (HA) coating-Ti-6Al-4V (implant I) and an HA coating-Ti (implant II) was performed. The bone-implant interface and tensile failure mode were evaluated by light microscopy (LM), SEM-energy dispersive X-ray analysis, and backscattered electron imaging. The crystallinity of the HA coating of implant I and implant II was 62 and 40%, respectively. Eleven semidisk implants of each type were inserted in the left tibia of 22 rabbits in each period. After 2, 4, 8, and 16 weeks, the tensile strength of the bone-implant I was 0.86, 1.32, 1.10, and 0.92 MPa, respectively; the value of the bone-implant II was 0.66, 0.92, 0.84, and 1.12 MPa, respectively. No significant difference was found in tensile strength between implant I and implant II, and between the data of different periods. LM and SEM revealed that the two types of coatings behave the same in bone. Failure after the tensile test mainly occurred at the bony tissue at 2 and 4 weeks, inside the HA coating layer at 8 weeks, and at the HA coating-metal substrate interface at 16 weeks. Degradation and delamination of the HA coating continued with time, resulting in the interfacial tensile strength not increasing with time. Thus, we concluded that differences between the two implants, mainly the difference in crystallinity of the HA coating (62 vs. 40%), have no significant influence on bone bonding ability, bone bonding strength, tensile failure mode, and degradation of the coating. © 1998 John Wiley & Sons, Inc. J Biomed Mater Res (Appl Biomater) 43: 113–122, 1998
35 citations
TL;DR: In this paper, a cage-like polynitrogen cluster N18 with symmetry C2v has been optimized at the RHF/4-31G∗ level.
Abstract: Ab initio quantum mechanics methods have been applied to study the cage-like polynitrogen cluster N18. The previously reported cage-like structure of the N18 molecule with symmetry C2v has been optimized at the RHF/4-31G∗, RHF/6-31G∗, DFT(B3LYP, B3P86, BHLYP)/6-31G∗ and MP2(full)/6-31G∗ levels of theory. The harmonic vibration frequencies and their infrared (IR) and Raman intensities have also been reported at RHF/4-31G∗, RHF/6-31G∗, as well as the B3P86/6-31G∗ level. The results show that the investigated cage-like structure is stable on the potential energy hypersurface, lying above separated nitrogen molecules by about 50 kcal mol−1 of nitrogen atoms, with a stability comparable with the dodecahedral N20 molecule. The resultant structure also suggests the aromaticity of conjugated pentagons which stabilizes the cage-like polynitrogen clusters.
35 citations
TL;DR: In this paper, the bilocal field generated by the mesons a and a in the global color symmetry model (GCM) has been determined in the instanton dilute liquid approximation.
Abstract: It is shown in this paper that the vacuum configuration of the bilocal field in the global color symmetry model (GCM) can be calculated in the instanton dilute liquid approximation. As only the excitation of Goldstone bosons is taken into account, the relative motion against the vacuum is equivalent to the dynamical mass of a quark. The bilocal field generating the mesons a and a in the GCM is then determined. With the determined bilocal field and the effective action, the masses and the decay constants of the mesons a and a, and the decay width of sigma --> pi pi are calculated in the GCM. The calculated results agree with experimental data quite well.
TL;DR: In this paper, RuCl2(PPh3)(BISBI) 1, RuHCl(CO)(PPh 3)(BisBI) 2 and RuH2(CO)(Pph3) 3, have been prepared and their compositions and structures were characterized by 31P{1H}-nMR, 1H-NMR and elemental analysis.
TL;DR: The conformational energy order of 1,3-difluoropropane is identified as GG < AG < AA < GG at various ab initio calculation levels in this paper.
Abstract: The conformational energy order of 1,3-difluoropropane is identified as GG < AG < AA < GG‘ at various ab initio calculation levels. This result is analyzed on the basis of the molecular structures,...
TL;DR: A modified two temperature vapor transport procedure has been used to synthesize AgGaS 2 polycrystalline materials at 1060 °C from high-purity Ag, Ga, S elements as discussed by the authors.
Abstract: A modified two temperature vapor transport procedure has been used to synthesize AgGaS 2 polycrystalline materials at 1060 °C from high-purity Ag, Ga, S elements. The results showed that the polycrystalline materials are pure single phase AgGaS 2 by X-ray powder diffraction analysis. The polycrystalline ingot includes a few interior voids and has a high mass density. The AgGaS 2 ingot with 12 mm in diameter and 20 mm in length has been grown by the modified Bridgman technique in two-zone vertical furnace. As-grown AgGaS 2 ingot was characterized by the X-ray diffraction technique, obtained the rocking curve of the crystal (011) face, it is shown that the ingot is AgGaS 2 single crystal. The infrared transparent of the crystal at 2 ∼ 10 μm is 49% (and absorption coefficient is 0.74 cm -1 ).
TL;DR: In this paper, a chiral lipophilic sulfur-containing macrocyclic ligand 5 with bis-pendant alcohols in the proximity of the coordination center has been synthesized and its metal ion complexes have been investigated as catalysts for the enantioselective hydrolysis of long chain α-amino acid esters in aqueous comicellar solution with Brij35.
Abstract: A novel chiral lipophilic sulfur-containing macrocyclic ligand 5 with bis-pendant alcohols in the proximity of the coordination center has been synthesized. Its metal ion complexes have been investigated as catalysts for the enantioselective hydrolysis of long chain α-amino acid esters in aqueous comicellar solution with Brij35. Large rate accelerations (up to 220 times) and moderate enantioselectivities (up to 4.85 (kS/kR)) employing the macrocyclic 5-Cu2+ have been observed, whereas the acyclic 3-Cu2+ exhibits less reactivity and stereoselectivity. Taking the analogous ligand 4, lacking the hydroxy groups leads to a dramatic rate decrease, and an inversion of enantioselectivity is observed. The pKa value of the hydroxyl bound to Cu2+ is determined to be pKa=7.2 under our micellar reaction conditions.
TL;DR: In this article, a new ligand BDNA [1,8-bis(diphenylphosphinomethyl)naphthalene] and three ruthenium complexes containing it were synthesized.
TL;DR: In this paper, the authors improved the results obtained by Bourque and Ligh in 1993 by obtaining new lower bounds for det[( x i, x j )], which improved the result obtained by Rajarama Bhat in 1991.
TL;DR: By using the spin-orbit coupling mechanism and the superposition model, the local environment of the Fe3+ ion in Al2O3 crystal is studied from its EPR data as mentioned in this paper.
Abstract: By using the spin-orbit coupling mechanism and the superposition model, the local environment of the Fe3+ ion in Al2O3 crystal is studied from its EPR data. From the studies, it is found that the Fe3+ ion does not occupy the exact Al3+ site, but, due to its larger size than the replaced host ion, it is forced to move towards the bigger oxygen triangle. It appears that the displacement direction of impurity ion in corundum-type structure depends not only upon the charge of impurity, but also upon its size. (C) 1998 Elsevier Science B.V. All rights reserved.
TL;DR: The main theses are that the construct P-PrTop of probabilistic pretopological spaces is the extensional topological hull of the construct FTPcs of FT-diagonal Probabilistic convergence spaces for every triangular norm T.
Abstract: The purpose of this paper is to discuss some categorical properties of probabilistic convergence spaces. Its main theses are: (1) the construct P-PrTop of probabilistic pretopological spaces is the extensional topological hull of the construct FTPcs of FT-diagonal probabilistic convergence spaces for every triangular norm T; (2) the construct P-PsTop of probabilistic pseudotopological spaces is the topological universe hull of FTPcs for every triangular norm T.
TL;DR: In this article, the authors prove new equilibrium existence theorems for non-compact abstract economies with an uncountable number of agents, and prove that the existence of such a non-convex economy can be achieved with an arbitrary number of nodes.
01 Oct 1998-Nuclear Instruments & Methods in Physics Research Section B-beam Interactions With Materials and Atoms
TL;DR: In this paper, the depth profile and chemical states of the implanted niobium in (0 1 1 2) sapphire after annealing with a series of steps from 500∘c to 1100∘C in a reducing atmosphere were determined.
Abstract: X-ray photoelectron spectroscopy (XPS) has been used to determine the depth profile and chemical states of the implanted niobium in (0 1 1 2) sapphire after annealing with a series of steps from 500∘C to 1100∘C in a reducing atmosphere. It is found that such an annealing procedure for the 380 keV niobium with a dose of 5×1016 ions/cm2 implanted into (0 1 1 2) sapphire at room temperature causes Nb migration towards the surface and results in a two-peak feature distribution profile with the large peak at the surface. The implanted niobium in sapphire is in different local environments with different charge states after annealing. Higher charge states of Nb+5 and Nb+4 are distributed mainly in the near surface region due to oxidation under environment. The metallic state was caused by annealing in reducing atmosphere and was distributed mainly in the sub-surface region with a profile of two-peak feature. The other charge states such as Nb+2 and Nb+1 may be associated with the defects retained in sapphire and distributed to deeper distance. The concentration of each charge state of niobium with depth is also presented in this paper.
TL;DR: In this article, the high-order perturbation formulas of EPR zero-field splittings D, E and g-factors g(i) (i = x, y, z) for d(3) ions in orthorhombic symmetry were established by using a two-spin-orbit coupling parameter model, in which both contributions from the spinorbit coupling of the central d3 ion and that of the ligands are included.
Abstract: In this paper, the high-order perturbation formulas of EPR zero-field splittings D, E and g-factors g(i) (i = x, y, z) for d(3) ions in orthorhombic symmetry are established by using a two-spin-orbit coupling parameter model, in which both contributions from the spin-orbit coupling of the central d3 ion and that of the ligands are included. Based on these formulas, the EPR parameters for the Cr3+ ion at an orthorhombic defect site in the AgBr crystal are calculated by considering the suitable defect-induced lattice distortion. The calculated parameters D and E show good agreement with the observed values. The reasons for the disparity of the g(i)-shift Delta g(i) = (g(i) - g(s)) between the calculation and the experiment and the importance of the contributions to the EPR parameters from the spin-orbit coupling of ligands are discussed.
TL;DR: In this article, the ab initio potential energy surface of the Ne-OCS complex is used to calculate the rovibrational bound states for the five isotopomers (Ne−OCS, 22 Ne-OCS, Ne−OC 34 S, NeO 13 CS, Ne-18 OCS) with a vibrational SCF-CI procedure.
TL;DR: In this paper, the authors generalized Lie bialgebras and Lie bi-gebioids to new objects which they call generalized Lie bilinear gebras, which are self-dual and generate canonically Hamiltonian structures on their representative spaces.
Abstract: We generalize Lie bialgebras and Lie bialgebioids to new objects which we call generalized Lie bialgebras. Similar to Lie bialgebras and Lie bial-gebroids, generalized Lie bialgebras are self-dual and generate canonically Hamiltonian structures on their representative spaces. We show that for a generalized Lie bialgebra (E, Ē), a pair (L 1,L 2) of E +Ē is again a generalized Lie bialgebra iff (L 1,L 2) is a Dirac structure pair . Construction of generalized Lie bialgebras by using Poisson tensors and Hamiltonian operators are also discussed in detail and an example relating to an infinite-dimensional integrable system is given.
01 Sep 1998
TL;DR: In this paper, the authors give an explicit description of the construction of inverse local limits in the category of locales and show a localic version of Steenrod's theorem without the Axiom of Choice.
Abstract: We give an explicit description of the construction of inverse
limits in the category of locales and show a localic version of Steenrod's theorem without
the Axiom of Choice; as an application we generalize the classic result by Steenrod.
TL;DR: Poly(vinyl chloride) membrane strontium ion-selective electrodes were developed by using three lipophilic diamides containing pyridine ring as ionophores using o-nitrophenyloctyl ether as plasticizing solvent.
TL;DR: The results showed that the polarity of this chromatographic column is mean-weak; the chemical and thermal stabilities and the selectivity are good and the operating temperature range is wide.
TL;DR: The unique positive equilibrium of a Lotka-Volterra system with a weakly diagonally dominant interaction matrix is globally stable as mentioned in this paper, which is the only known positive equilibrium in the literature.
TL;DR: It is demonstrated that the amino groups and carboxyl groups of the side chains in thegelatin do not undergo the chelation reaction with Cr iii in the sensitive area.
Abstract: A new, to our knowledge, method of modifying methylene blue
dichromated-gelatin (MBDCG) holograms by use of ninhydrin and
removal of their amino groups and carboxyl groups, which strongly
adsorb humidity, has been developed. The modified MBDCG holograms
are stable for 1000-line/mm gratings (diffractional efficiency of
95%) in a high-humidity environment (relative humidity of
80%–85%). The modifying reaction does not affect the
diffraction efficiency of the MBDCG holograms. It is demonstrated
that the amino groups and carboxyl groups of the side chains in the
gelatin do not undergo the chelation reaction with Cr iii
in the sensitive area.
TL;DR: In this article, a topological degree for a class of mappings of the form F=L+S where L is closed densely defined maximal monotones operator and S is a nonlinear multivalued map of class (S+) with respect to the domain of L is given.
Abstract: This paper is to generalize the results of Zhang and Chen[1]. We construct a topological degree for a class of mappings of the form F=L+S where L is closed densely defined maximal monotones operator and S is a nonlinear multivalued map of class (S+) with respect to the domain of L.