Positive periodic solutions of higher-dimensional nonlinear functional difference equations

In this paper, we apply a cone theoretic fixed point theorem to obtain sufficient conditions for the existence of multiple positive periodic solutions to the higher-dimensional functional difference equations of the form:

Existence of positive solutions in a delay logistic difference equation

The author studied the existence of positive solutions of the delay logistic difference equationΔyn=pnyn(1-yτ(n)), n=0,1,2,....where {pn} is a sequence of positive real numbers, {τ(n)} is a nondecreasing sequence of integers, τ(n)＜n and limn→∞τ(n)=∞. A sufficient condition for the existence of positive solutions of the equation was given.     

K-bitonic sort

Ak-bitonic sort which generalizes the bitonic sort is proposed. The theorem of the bitonic sort, which merges two monotonic sequences into one order sequence, is extended into the theorem ofk-bitonic sort. Thek-bitonic sort merges (K (=2k or 2k−1) monotonic sequences into one order sequence in steps, where is an integer andk≥1. Thek-bitonic sort is the Batcher's bitonic sort whenk=1. Project supported by the National 863 Foundation of China (863-306-05-01-1) and the National Natural Science Foundation of China (Grant No. 69673037).     

Optical Characteristics of Porous Glasses Matrix and Its Light-conducted Mechanism

The optical properties of matrix of porous glasses and phase separated glasses were investigated by visible spectroscopy and infrared spectroscopy.The experimental results show that.both the porous glasses and phase-separated glasses hare very good light transmission in visible ligth region that wavelenth is longer than 560nm.The micropores of porous glasses and the boron-rich phase of phase-separated glasses have strong Rayleigh scatter effects on the visible light.the largest scatter occurrs at 360-370nm;the thicker the glasses.the larger the light scattering.Thus .the pore size disribution and thed size of heterogeneous micro zone in boron-rich phase of phase-separated glasses can be measured .After coupled into porours glasses.the most intense absorption of hydrated ious of [Co(H2O) 6]^2 shifts from 508 nm to 515nm.The production of the most intense absorption and the red shift were owde to Jahn-Teller of octahedral field formed by six H2O moleculur and perturbation effect resulted by microporous of porous glasses for its physics-chemical cirumstance.As a result.the porous glasses are perfect optical function materials in risible region.ichich can be assembled by chenvical method.     

Semiviscosity flow equation with variable parameters under superplastic tension conditions

Ａｓｅａｒｌｙａｓｉｎ1964,Ｂａｃｋｏｆｅｎｅｔａｌ.ｂｅｌｉｅｖｅｄｔｈａｔｕｎｄｅｒｓｕｐｅｒｐｌａｓｔｉｃｃｏｎｄｉｔｉｏｎｓｈａｒｄｌｙａｎｙｓｔｒａｉｎｈａｒｄｅｎｉｎｇｔａｋｅｓｐｌａｃｅｄｕｒｉｎｇｔｈｅｄｅｆｏｒｍａｔｉｏｎｏｆｍａｔｅｒｉａｌｂｕｔｔｈｅｒｅｉｓａｓｔｒｏｎｇｓｔｒａｉｎｒａｔｅｈａｒｄｅｎｉｎｇ[1].Ａｎｄｔｈｅｙａｌｓｏｅｓｔａｂｌｉｓｈｅｄｔｈｅｓｅｍｉｖｉｓｃｏｓｉｔｙｅｑｕａｔｉｏｎσ=ｋεｍ,(1)ｗｈｉｃｈｉｎｄｉｃａｔｅｓｔｈｅｒｅｌａｔｉｏｎｂｅｔｗｅ…     

Synthesis and characterization of triclinic structural LiVPO4F as possible 4.2 V cathode materials for lithium ion batteries

A potential 4.2 V cathode material LiVPO4F for lithium batteries was prepared by two-step reaction method based on a carbon-thermal reduction （CTR） process. Firstly, V2O5, NH4H2PO4 and acetylene black are reacted under an Ar atmosphere to yield VPO4. The transition-metal reduction is facilitated by the CTR based on C→CO transition. These CTR conditions favor stabilization of the vanadium as V^3＋ as well as leaving residual carbon, which is useful in the subsequent electrode processing. Secondly, VPO4 reacts with ElF to yield LiVPO4F product. The property of the LiVPO4F was investigated by X-ray diffractometry （XRD）, scanning electron microscopy （SEM） and electrochemical measurement. XRD studies show that LiVPO4F synthesized has triclinic structure（space group p I ）, isostructural with the naturally occurring mineral tavorite, EiFePO4-OH. SEM image exhibits that the particle size is about 2μm together with homogenous distribution. Electrochemical test shows that the initial discharge capacity of LiVPO4F powder is 119 mA·h/g at the rate of 0.2C with an average discharge voltage of 4.2V （vs Ei/Li^＋）, and the capacity retains 89 mA·h/g after 30 cycles.     

Preparation and Properties of Dip-coated CeO2-TiO2 Thin Golden Glass Film

The golden and ultraviolet-absorbed CeO2-TiO2 film was prepared on soda-lime glass substrate with the thickness of 2 mm via the sol-gel method. The transmission spectra in range of 200 nm-800 nm were measured, and the crystallization, the abrasion and acid resistance were also investigated. The appropriate sol contents and heat-treatment schedule were determined. The results indicate that the appropriate molar ratio of Ce/Ti was 3：5 to 5：6. The ultraviolet-absorbance ability increased with the increase of the Ce/Ti molar ratio, but when the Ce/Ti molar ratio was higher than 1.5, the homogeneity of the film was deteriorated. With the increase of heat-treatment temperature, the main wavelengths of the color of the coated glasses were equal, but the color＇ s saturation decreased; the transmission peaks were the same, while the intensity of the peaks decreased. The roughness, abrasion and acid resistance of the film were also enhanced at the same time. The appropriate heat- treatment temperature may be 340℃.     

Infrared-to-green upconversion properties of Er^3＋/Yb^3＋ co-doped TeO2-TiO2-K2O glasses upon excitation with 976 nm lasers diode

The energy transfer and upconversion of Er^3＋/Yb^3＋ co-doped TeO2-TiO2-K2O glasses upon excitation with 976 nm lasers diode were studied. The tellurite glasses were prepared by conventional melting methods. Their optical properties and sensitization upconversion spectra were performed. The dependence of green upconversion lu- minescence intensity on the mole ratio of Yb^3＋ to Er^3＋ and Er^3＋ concentration were discussed in detail. When the mole ratio of Yb^3＋ to Er^3＋ is 25/1 and Er^3＋ concentration is 0.1% （mole fraction）, or when the mole ratio of Yb^3＋ to Er^3＋ is 10/1 and Er^3＋ concentration is 0.15 %, the optimal upconversion luminescence intensity is obtained. The obtained glasses can be one of the potential candidates for lasers-diode pumping microchip solid-state lasers.     

Fine structure and interface structure of ion-bombardment nitrided layers

ＧｅｒａｒｄｉｎａｎｄＭｉｃｈｅｌｏｂｓｅｒｖｅｄｔｈｅｉｏｎｎｉｔｒｉｄｅｄｌａｙｅｒｏｆｐｕｒｅｉｒｏｎｗｉｔｈＴＥＭ[1].Ｔｈｅｒｅｓｕｌｔｓｓｈｏｗｅｄｔｈａｔｔｈｅｒｅａｒｅｏｎｌｙｔｗｉｎｓ,ｓｏｗｈｅｔｈｅｒｔｈｅｒｅａｒｅｄｉｓｌｏｃａｔｉｏｎｓａｎｄｗｈａｔｉｓｔｈｅｉｒｃｏｎｆｉｇｕｒａｔｉｏｎａｒｅｎｏｔｑｕｉｔｅｃｌｅａｒ.Ｔｈｅａｕｔｈｏｒｓｈａｖｅｆｏｕｎｄｔｈａｔｔｈｅｒｅａｒｅｖａｃａｎｃｉｅｓｉｎｉｏｎｎｉｔｒｉｄｅｄｌａｙｅｒｓ[2],ｂｕｔｔｈｅｐｒｏｏｆｏｆａｔｏ…     

Synthesis and structural characterization of macroporous bioactive glass

Porous sol-gel glass of CaO-SiO2-P2O5 system with macropores larger than 100 μm was prepared by adding stearic acid as pore former when the sintering was carried out at 700 ℃ for 3 h. The sol-gel porous glass shows an amorphous structure. The diameter of the pore created by pore former varies from 100 to 300 μm, and macroporous glass has a narrow and small pore size distribution in mesoporous scale. The porosity and pore size ofmacroporous bioactive glass can be controlled.     

Effect of Thermal Treatment and Acid Leaching Process on Pore Characteristics of Nanometer Porous Glass

Porous glass was prepared by thermally treating sodium borosilicate glass for different time, the effect of thermal treatment on pore size distribution was discussed and the pore size of the prepared porous glass was measured by scanning electron microscopy （SEM） and differential thermal analysis （DTA）. The results show that the optimum porous glass with an average diameter of 80 nm can be prepared by thermal treatment at 600℃ for 12 h and then acid treatment for 12 h in 2 mol·L^-1 hydrochloric acid solution.     

Structure and Properties of the Lithium Aluminosilicate Glasses with Yttria Addition

The structure and properties of lithium aluminosilicate glasses containing Y 2 O 3 were investigated by X-ray diffraction(XRD),scanning electron microscopy(SEM),differential thermal analysis (DTA)and Raman spectroscopy.Effects of yttria on the viscosity of LAS glasses were investigated,and found that the introduction of yttria effectively decreased the viscosity of LAS glasses.In Raman spectra of initial glasses it is shown the starting glasses are in almost complete disorder,since all bands are weak and broad.In the spectra of heat-treated specimens some new narrow bands appear and increase in intensity,and the frequency changes with varied yttria addition.The DTA and XRD results show that yttria controlled the crystallization of LAS glasses by increasing the crystallization peak temperature(T p ),however,the main crystalline phase of glass-ceramics wasβ-spodumene.     

Microstructure and Optical Properties of the （1-x）GeS2-xP2S5 Glasses

To find materials with larger second-order nonlinearity, the Ge-P-S chalcogenide glasses with various ratios of GeS2 ： P2S5 were prepared by the melt-quenching method. The microstructure and optical properties of these glasses were characterized by XRD, Raman, Vis- NIR speetroscopy and Maker fringe technique. The second harmonic generation （SHG） was observed in the as-prepared chalcogenide glasses which was ascribed to the thermal stress gradient and/ or the rnicroanisotropic defects （ such as the lone-pair orbital or the valence alternative pairs ） prefer-orientation of the as-prepared glasses.     

The Mechanism of Sol-Gel Synthesis of Normal Spinel LiMn2O4 with Chelation of Citric Acid

The sol-gel process of citric acid chelating with metal cations for the synthesis of normol spinel LiMn2O4 and the reaction mechanion mechavism were investigated by means of XRD,TG-DTA,and SEM ,the results show that at the beginning lithium citrate and chelate compound of citic acid with manganese ions formed ,and then with heating the esterification and condensation reacions occured between them and glyol ,The products obtained are polymers in which metal cations are distibuted homogeneously on atomic scale that ensur hight reacivity to cations of Li^ and Mn^2 ,Firing the gel grepared by this process ,the lattice diffusions of solid reactant ions caused by non-homogeneity of reactants are elinimated and avoided .At 400℃ phase-pure LiMn2O4 with nanometer scale crystallization having precise stoichiometry and perfect crystallization can be obtained ,The model of chelate coordinated of double -molecule between citric acid and Mn^2 in the gel network is proosed ,It is important for explaining the dispersion state of Mn^2 and the formaiton process of gel by this model.     

Densification and sintering dynamics of 10NiO-NiFe2O4 composites doped with CaO

The effects of CaO content in the range from 0 to 4.0%, and sintering temperature on the phase composition, relative density and electrical conductivity of 10NiO-NiFe2O4 composites doped with CaO were studied. The results show that there is no change of structure for NiO or NiFe2O4; there is apparent oxygen absorbing and releasing behavior during the heating process in air for 10NiO-NiFe2O4 composites. Introduction of CaO can accelerate the densification of 10NiO-NiFe2O4 composites. The maximum value of relative density is 98.75% for composite doped with 2.0% CaO and sintered at 1 200 ℃, which is beyond about 20% for the undoped composites. The sintering activated energy of sample containing 2% CaO decreases by 15.87 kJ/mol, compared with that of the undoped sample.     

Dynamic recrystallization behavior of 35CrMo structural steel

1　ＩＮＴＲＯＤＵＣＴＩＯＮＤｕｒｉｎｇｈｏｔｗｏｒｋｉｎｇ ,ｓｅｖｅｒａｌｍｅｔａｌｌｕｒｇｉｃａｌｐｈｅｎｏｍｅｎａｓｕｃｈａｓｗｏｒｋ ｈａｒｄｅｎｉｎｇ (ＷＨ ) ,ｄｙｎａｍｉｃｒｅｃｏｖｅｒｙ (ＤＲＶ) ,ａｎｄｄｙｎａｍｉｃｒｅ ｃｒｙｓｔａｌｌｉｚａｉｔｏｎ (ＤＲＸ )ｏｃｃｕｒｓｉｍｕｌｔａｎｅｏｕｓ ｌｙ[1 5 ] .Ｅｓｐｅｃｉａｌｌｙ ,ｔｈｅｏｃｃｕｒｒｅｎｃｅｏｆＤＲＸ ,ｃａｎｒｅｆｉｎｅｇｒａｉｎａｎｄｒｅｄｕｃｅｄｅｆｏｒｍａｔｉｏｎｒｅｓｉｓｔａｎｃｅｉｎｐｒａｃｔｉｃａｌｈｏｔ ｗ…     

Effect of Electron Beam on the Structure and Crystallization Features of BaO-SrO-TiO2-SiO2 Glass

Glasses of BaO-SrO-TiO2-SiO2 after electronic radiation treatment of 50-1000 kgy were studied by means of IR spectra, DTA and visible light absorption method. The result shows that the glass structure is changed due to the formation of structue defect from oxygen vacancy and E‘color center, which resultsd in the crystallization process and new precursors, and decreasement of Tg temperature and crystallization peaks by 20 -50℃.     

Preparation and Properties of Ag—TiO2 Thin Films on Glass SUbstrates

Ag-TiO2 thin films were prepared on glasses.The morphology and structure of Ag-TiO2 films were investigated by XRD.SEM and FT-IR.The photocatalytic and hydrophilic properties of Ag-TiO2 thin films were also evaluated by examining photocatalytic degradation dichlorophos under sunlight illumination and the change of contact angle respectively.The research results show that the Ag-TiO2 thin film is mainly composed of 20-100nm Ag and TiO2 particles,The Ag-TiO2 thin films possess a super-hydrophilic ability and higher photocatalytic activity than that of pure TiO2 thin film.     

Influence of TiO<Subscript>2</Subscript> on the alkali resistance and structure of invert glass

Through measuring the alkali resistance of the invert glass and the quanity of SiO₂ and TiO₂ migrating fron the glass into the solution, the influence of TiO₂ on the alkali resistance of the glass is discussed and its structure is also analyzed by infrared spectroscopy. It is concluded that TiO₂ has double functions for the alkali resistance of the invert glass. On the one hand, both TiO₂ polarizing the secondary ions in glass and TiO₂ isomorphism replacement of SiO₂ make the alkali resitance of the glass decrease. On the ther hand, TiO₂ patching network and anti-erosion covering help to increase the alkali resistance. ZHAO Qing-lin: Born in 1972 Funded by the National Natural Science Foundation of China(No. 59372081)     

Interface structure of Ag (111)/SnO<Subscript>2</Subscript> (200) composite material studied by density functional theory

Electric contact material of Ag/SnO₂ was successfully synthesized by in situ process method. The interface structure was characterized by high-resolution transmission electron microscopy (HTEM) and simulated at atomic scale on computer. The mean-square displacements of atoms near the interface were calculated, and the results showed that near the interface both Ag side and SnO₂ were mismatched and this effect decays rapidly far from the interface. By inspecting the calculated density of states (DOS), we found that the electric-conductivity of this composite material was decreased because of the localized 4d and 2p electrons of Ag and O near the Fermi surface, respectively. Electron density changed acutely across the interface, so that there was no extra compound precipitated. A micro-electric field also formed in the whole material due to the interface structure, and this may affect the electron conduction and the related electric-conductivity of the composite. It is found that the interface cohesive energy of Ag (111)/SnO₂ (200) was −3.50 J/m², which is higher than the experimental results. Supported by the National Natural Science Foundation of China (Grant No. 2008CB617609), the Natural Science Foundation of Yunnan Province (Grant No. 2006E003Z) and Science Innovation Foundation of Kunming University of Science and Technology