Structure characteristics and electrochemical properties of LiMn2O4 modified by LiCoO2

In order to improve the cycle performance of LiMn2O4, the modified LiMn2O4 was prepared by solid-state reactions using LiMn2O4 and LiCoO2 as precursors. XRD and EDS were used to study the structure properties of the modified LiMn2O4. The electrochemical properties of the modified LiMn2O4 were also investigated, The results show that Li and Co atoms could insert into the LiMn2O4 crystal lattice and a newly formed spinel phase, modified LiMn2O4 was obtained. The modified LiMn2O4 exhibits excellent cycle ability at room and elevated temperatures compared to pure LiMn2O4. The improved electrochemical stability of the modified LiMn2O4 attributes to the entrance of Li and Co ions inserted into the spinel crystal structure.     

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.     

Electrochemical Characterization of Surface-modified LiMn2O4 Cathode Materials for Li-ion Batteries

To improve the performance, the surface of 12Mn2O4 was coated with very fine MgO , Al2O3 and ZnO by solgel method, respectively. The structure and morphology of the coated materials were investigated by X-ray diffraction （ XRD ）, X-ray photoelectron spectroscopy （ XPS ） and scanning electron microscopy （SEM）. The charge and discharge performance of uncoated and surfnce modified 12Mn2O4 spinel at 25℃ and 55 ℃ were tested, using a voltage window of 3.0-4.35 V and a current deasity of 0. 1 C rate. There is a slight decrease in the initial discharge capacity relative to that of uncoated UMn2 O4, bat the cycle ability of 12 12Mn2O4 coated by metal-oxide has remarkably been improved. The EIS measuremeuts of uncoated and Al2O3 -coated 12Mn2O4 were carried out by a model 273 A potentiostatl galvanistat controUed by a computer using M270 software, and using a freqnency response analyzer （ Zsimpwin ） combined with a potentiostate （ PAR 273）. Coaseqnently, the reason for the improved cycle properties is that the surface modification reduces the dissolution of Mn , which results from the suppression of the electrolyte decomposition, and suppresses the formation of passivation film that acts as an electronic insulating layer. In conclusion, the use of surface modification is an effective way to improve the electrochemical performance of 12Mn2O4 cathode material for lithium batteries.     

Sol—Gel Synthesis of Normal Spinel LiMn2O4 and Its Characteristics

Normal spinel LiMn2O4 was synthesized by sol-gel method using lithium nitrate,manganese nitrate,citric acid and ethylene glycol as raw materials.LiMn2O4 was characterized by XRD,TG-DTA,IR,SEMand AAS,The optimum conditions for the synthesis were explored.Citric and ethylene glycol were mixed with molar ratio of 0.25,and the mixtrue was esterified at 140℃ for 4 hours.Then lithium nitrate and manganese nitrate were added with molar ratio of 0.6,In the system,the total molar of cations was equal to that of citric acid.At last,reflux the system at 105℃ for 2 hours,Dried gel was fired at 600℃ for 8 hours.Particle diameters of raw product were about 100nm mainly.Further research shows that lithium ion of LiMn2O4 is easy to be extracted,and normal spinel λ-MnO2 can be obtained after lithium ion extraction.     

Thermodynamic Analysis of Desul furization of Fine Coal by Electrochemical Reduction FIotation

Problems in desulfurization of coal by electrochemical reduction is analyzed and calculated. The result shows that 1 ) the △rGm function of the reaction of pyrite into FeS and the modifying reaction decreasing the oxygenous functions on coal surface is smaller than zero in a spontaneous reaction, and greater than zero in a non-spontaneous reaction; 2) the △rGm value can be adjusted by pH and the dosage of electrolyte to make it be greaterthan zero , which is favorable for the modifying reaction and useful for desulfurization of coal. The research has provided a theoretical foundation for determining reasonable technical parameters of desulfurization。     

Thermodynamic Analysis of Desulfurization of Fine Coal by Electrochemical Reduction Flotation

Problems in desulfurization of coal by electrochemical reduction is analyzed and calculated. The resultshows that 1) the △_rG_m function of the reaction of pyrite into FeS and the modifying reaction decreasing theoxygenous functions on coal surface is smaller than zero in a spontaneous reaction, and greater than zero in a non-spontaneous reaction; 2) the △_rG_m value can be adjusted by pH and the dosage of electrolyte to make it be greaterthan zero, which is favorable for the modifying reaction and useful for desulfurization of coal. The research hasprovided a theoretical foundation for determining reasonable technical parameters of desulfurization     

Modified fuzzy point estimate method and its application to slope reliability analysis

A slope engineering system is a complex system, in which many uncertainties exist, including random uncertainties and fuzzy uncertainties. Traditionally, random uncertainties were often considered, while fuzzy uncertainties were ignored. Therefore, fuzzy-random methods should be proposed. A fuzzy point estimate method was proposed by Dodagoudar, that is, considering the effect of fuzzy-random factors, the fuzzy-random limit state function of slopes is changed to random interval limit state function by the A level cutting, then the moments of the function can be obtained by the Rosenblueth's method, and the stability state of slopes can be evaluated by synthesizing a group of moments. But in Dodagoudar's method, Rosenblueth's state function is composed of only two kinds of combinations of parameters rather than 2" kinds of combinations. So a modified fuzzy point estimate method is proposed by the authors, and it is used in a slope reliability analysis.     

Influence of rare earth modification and homogenization on the microstructure and mechanical properties of recycled can 3004 aluminum

The microscopic structure of waste can aluminum material was researched by adding Al5TiB refining agent, La-Ce rare earth and mixed rare earth modifiers, and the microstructure and mechanical performance of the modified aluminum material were studied. The experimental results show that the optimal refiner addition amount is 1.1wt%; the material performance can be significantly improved when the content of La-Ce rare earth ranges to a certain degree, but the mixed rare earth barely affects the refinement effect of the aluminum. When being homogenized, the mixed rare earth plays more obvious role in refining the aluminum material than La-Ce rare earth. The optimal plan is modifying the aluminum material with 3wt% mixed rare earth and homogenizing with annealing temperature of 580 ℃, annealing time of 12 hours and heating rate of 5 ℃/min while refining the material with 1.1wt% Al-5Ti-1B.     

Electrochemical properties of spinel LiMn2O4 and LiAl0.1Mn1.9O3.9F0.1 synthesized by solid-state reaction

Two types of spinel cathode powders, LiMn2O4 and LiAl0.1Mn1.9O3.9F0.1, were synthesized by solid-state reaction. X-ray diffraction (XRD) patterns of the prepared samples were identified as the spinel structure with a space group of Fd 3 m. The cubic lattice parameter was determined from least-squares fitting of the XRD data. The LiAl0.1Mn1.9O3.9F0.1 sample showed a little lower initial capacity, but better cycling performance than the LiMn2O4 sample at both room temperature and an elevated temperature. The Vanderbilt method was used to test the electrochemical conductivity of the LiMn2O4 samples. The electrochemical impedance spec-troscopy (EIS) method was employed to investigate the electrochemical properties of these spinel LiMn2O4 samples.     

Nano K2Ti4O9 Whisker Enhanced Solid Lubrication Coating for Cutting Application

In order to decrease catting fluid and improve envirorunent, the catting fluid was replaced by solid lubricant. Four kinds of solid lubricants were tested on a high temperature friction tester, from which nano K2Ti4O9 whisker enhanced solid lubrication film was chosen. It was coated on the surface of catters and tested on a CA6140 lathe. At the rate of4OOr/min, the wear of the tool flank with solid lubrication,film is 1/6 of that without the film and it is even lower than that using catting fluid. With the increase of catting speed, the wear of the tool flank with solid lubrication,film is still lower than that without ,film, bat it is higher than that using catting fluid. Surface analyses by AFM , SEM and EDX reveal that the solid lubrication ,film can prevent Fe element of chips from diffusing the cutter surface ; adhesion of the cutter and chips is abated and the wear of the tool flank is obviously decreased.     

Finite difference method for dynamic response analysis of anchorage system简

Based on some assumptions, the dynamic analysis model of anchorage system is established. The dynamic governing equation is expressed as finite difference format and programmed by using MATLAB language. Compared with theoretical method, the finite difference method has been verified to be feasible by a case study. It is found that under seismic loading, the dynamic response of anchorage system is synchronously fluctuated with the seismic vibration. The change of displacement amplitude of material points is slight, and comparatively speaking, the displacement amplitude of the outside point is a little larger than that of the inside point, which shows amplification effect of surface. While the axial force amplitude transforms considerably from the inside to the outside. It increases first and reaches the peak value in the intersection between the anchoring section and free section, then decreases slowly in the free section. When considering damping effect of anchorage system, the finite difference method can reflect the time attenuation characteristic better, and the calculating result would be safer and more reasonable than the dynamic steady-state theoretical method. What is more, the finite difference method can be applied to the dynamic response analysis of harmonic and seismic random vibration for all kinds of anchor, and hence has a broad application prospect.     

Cspacity fading of spinel LiMn2O4 during cycling at elevated temperature

A normal spinel LiMn2O4 as cathode material for lithium-ion cells was cycled galvanostatically (0.2C) at 55℃ .To determine the contribution of each voltage plateau to the total capacity fading of the cathode upon repeated cycling,the capacities in each plateau were separated by differentiation of voltage vs,capacity.The results show that the capacity fading in the upper voltage plateau is more rapidly than that in the lower during discharging,while in charging process,it fades slower than that in the lower voltage range.The increased capacity shift and aggravated self-discharge/electrolyte oxidation during discharging contribute to a high fading rate in the upper step.Capacity shift also takes place during charging process,which again enhancing the fading rate of the lower voltage plateau.An increase in capacity shift,as a result of an increase in polarization of the cell.plays a major role in determining the fading rate in each voltage plateau,further reflecting the thickening of the passivation layer on the active particles,and the accumulation of electrolyte decomposition.The relative capacity loss for modified spinels is well correlated with the relative increase in the polarization of the half-cells.confirming the above causes for capacity fade of this kind of cathode material.     

The New Technology of Composite Materials Repairing by Light Wave

The repairing of damaged composite materials becomes a hot research subject in the late 1990s.In this paper a new technology of repairing composite materials is given on the basis of our previous research. The light wave of 675run transmitted by optical fiber is used as repairing light source, special repairable adhesive which can be stimulated by the light is adopted. By comparing the stiffness of the composite material before and after being damaged, it can be concluded that the mechamical property will not be changed with the feasible repairing teehnology.     

Combination of hydrophobically modified γ-poly (glutamic acid) and trehalose achieving high cryosurvival of RBCs

Trehalose is expected to be an alternative for toxic glycerol as a biocompatible cryoprotectant of red blood cells(RBCs). In this work, γ-poly(glutamic acid)(PGA) is modified by grafting hydrophobic phenethylamine, 3,4-dimethoxyphenylethylamine and dodecylamine, respectively. The graft-modified PGA can significantly enhance cryosurvival of RBCs in combination with trehalose. Analyses of dynamic light scattering, hemolysis assay, atomic force microscope and confocal laser scanning microscope suggest that the modified PGA polymers can self-assemble into nanoparticles in phosphate buffer saline solutions at the pH range of 6.0–7.4, and exhibit membrane-disruptive activity due to hydrogen bond, conjugation and hydrophobic interactions with cell membranes. It is assumed that the modified PGA polymers can improve the cryosurvival of RBCs by promoting membrane permeability of trehalose. Among the three graft-modified polymers, phenethylamine-grafted PGA(PGA-g-PEA)can significantly increase the intracellular trehalose-loading content to 11.3±2.4 m M at pH 7.4, much higher than the value0.17±0.66 m M when trehalose is used without any polymers. In view of the aforementioned merit, the cryosurvival rate of sheep RBCs is increased to about 90% by incubation with 1.0 mg mL~(-1) PGA-g-PEA and 0.36 M trehalose. In vitro cell culture of L929 fibroblasts demonstrates low cytotoxicity of PGA-g-PEA. Therefore, hydrophobic PEA-modified PGA with enhanced intracellular trehalose-loading ability can be potentially applied in glycerol-free RBC cryopreservation or other related biomacromolecule delivery systems.     

Synthesis of SrTiO3 for immobilization of simulated HLW by SHS

Strontium titanate synroc samples were synthesized by self-propagating high-temperature synthesis （SHS）. Sr directly took part in the synthesis process. As a result, the loading content issue is basically resolved. The products were characterized by density, microhardness X-ray diffraction, and scanning electron microscopy （SEM/EDS）. The leaching rate was measured by the method of PCT （product consistency test）. The results indicate that the Sr^2＋-SrTiO3 compound is of high density, low leach rate and high stability and the synthesis process is feasible in technology and economy. It can be concluded that the strontium titanate synroc is a perfect material to immobilize HLW.     

EVALUATION OF SAND RECLAIMED BY DRY TYPE VIBRATION METHOD

It is customary to evaluate the sand reclamation efficiency by general standardmethod as sieve analysis etc.But the special method also can be used in the casewhere the weight of specimen sand is small and a more accurate result is expected.Inauthors'experiments,the grain-size analysis was carried out by an image analysingcomputer and the Na_2O content analysis was done with a modified standard methodof acid consumption.From the results of analyses,it might be recognized that theCO_2-sodium silicate bonded sand can be reclaimed by dry type vibration methodeffectively after pretreatment.The size and form of reclaimed sand grain are the sameas those of original new Sand and soda content in the remainder on the surface ofsand grain is about 0.I%.It is assumed that the sieve method may be replaced by theimage analysing computer in sand grain-size analysis in the future.It is also pro-posed that the titration method for measuring Na_2O content may be necessary tobe studied further.     

Preparation of 3,4-Dihydro-2H-pyran Catalyzed by Modified Gamma Alumina

A promising catalytic material, modified gamma alumina with high surface area (300m2/g )and higher contents of strong acid sites was developed. It was prepared by a special precipitation method with aluminum nitrate solution containing a certain amounts of orthosilicic acid and ammonia aqueous solution. Compared with commercial gamma alumina, the modified gamma alumina is an effective catalyst for dehydration of tetrahydrofurfuryl alcohol to 3,4-Dihydro- 2 H-pyran. Under the optimized reaction conditions, an improved yield of 3,4-Dihydro-2H-pyran of 93.4% was achieved. The profiles of pyridine TPD slow that the modified gamma alumina exhibits more strong acid sites than that in the commercial gamma alumina, indicating the strong acid sites on the surface of the catalyst may play a crucial role in this reaction.     

Numerical study on deformation and failure of reinforced sand

In order to investigate the deformation and failure of reinforced sand, and the reinforcing mechanism of flexible and rigid reinforcement, a set of plane strain compression tests of dense Toyoura reinforced sand with planar reinforcement of a wide range of stiffness were analysed by a nonlinear finite element method. The analysis was incorporated into an energy-based elasto-plastic constitutive model for sand to develop a stress path-independent workhardening parameter based on the modified plastic strain energy concept. Numerical results indicate that the global stress-strain relations of sand specimens are reinforced by using relatively flexible and rigid reinforcement, and an unreinforced sand specimen can be reasonably simulated by the current finite element method. It is also found that the reinforcing mechanism and progressive failure with a development of shear bands in reinforced sand can be reasonably examined by the finite element method.     

DEVELOPMENT OF LIGNIN EPOXIDE-A POTENTIAL MATRIX OF RESIN MATRIX COMPOSITE

To develop new kinds of matrix resin of composite and utilize lignosul fonate in large scale and high value, a kind of lignosulfonate was modified into epoxide in this paper. Two kinds of phenolized lignosulfonic acid and two kinds of lignin epoxides were prepared. The lignin epoxides and a kind of bisphenol—A epomy resin were mixed respectively with a kind of liquid anhydride (MNA) to be measured by DSC technology. Both of these two kinds of epoxides can be cured by MNA, and curing exotherm of the liquid one is more than that of the solid one. Samples of the phenolized lignosulfonic acid and the epoxides were all analyzed by IR spectroscopy to find relations between them. It is suggested that the phenolation decide the type and the yield of the lignin epoxides.     

Iterative FEA Method for Load Distribution of Flexible Supporting Thin-section Ball Bearing

To figure out the load distribution of thin-section rolling bearing supported by flexible structure with squirrel cage and the distribution’s influence on bearing life,an iterative FEA method is proposed to use the result calculated from the Quasi-Dynamic model based on the rigid support hypothesis. The contact angle,contact position and stiffness of equivalent spring are modified during the iterative FEA to optimize the FEA model,and then the bearings’ life can be predicted when the error is below 0.5%. It can be concluded that from the analysis results the load distribution under flexible support is more uniform than that of the rigid support,while the maximum load decreases by 11.2% and bearing life increases by 14.7%. The analysis result of different values of thickness of bearing house,rings and hollow shaft demonstrates the thicknesses of bearing house and hollow shaft have a greater influence on the load’s uniformity and bearing’s life than those of the rings.