β-SiC nanoparticle reinforced Al matrix (nano-SiCp/Al) composite was prepared by a multistep powder metallurgy strategy including presureless sintering, hot compacting process and hot extrusion. The microstructures of the as-prepared composites were observed by scanning electronic microscopy (SEM), and the mechanical properties were characterized by tensile strength measurement and Brinell hardness test. The experimental results revealed that the tensile strength of the composite with the addition of 5wt% β-SiC nanoprticles could be increased to 215 MPa, increasing by 110% compared with pure Al matrix. Comparative experiments reflected that the β-SiC nanoprticles showed significant reinforcement effect than traditional α-SiC micro-sized particles. The preparation process and sintering procedure were investigated to develop a cost effective preparation strategy to fabricate nano-SiCp/Al composite.

With the pulsed laser deposition (PLD) method, amorphous 80GeS₂-15Ga₂S₃-5CdS chalcogenide film was deposited on glassy substrate. Obvious second harmonic generation (SHG) was observed in the ultraviolet (UV)-polarized film and the SHG intensity increased with the increase in single pulse energy and irradiation time. Through Raman spectra and transmission spectra, the mechanism of SHG was studied. The experimental results demonstrated that effective electron traps and hole traps were generated in the UV-polarized film. The energy of electrons and holes was using up due to the collision with other particles and crystal fields during their movement and finally they were captured by the traps and fixed, which made the electric charge distribution nonuniform in the film and destroyed the spatial isotropy. In the meantime, the center of positive and negative charges separated and a built-in electric field was formed which generated the optical second-order nonlinearity of the film.

The Zn²⁺, Ni²⁺ and Co³⁺ doped Sr₁₄Cu₂₄O₄₁ compounds were synthesized by standard solid state method. X-ray diffraction results show that the changes in lattice parameters are very small. Selected area electron diffraction patterns (EDPs) show that the diffraction spots corresponding to the CuO₂ chain substructure are extended to streaks along a* and b* directions for all the samples, while the diffraction spots produced merely by the Cu₂O₃ ladder substructure are still very sharp. This means that the periodicities of chains in a* and b* directions are partially destroyed upon doping of Zn, Ni and Co due to that the initial phase of each chain becomes a random variable. The temperature dependence of magnetic properties was measured for every sample. And the number of dimers in CuO₂ chain per formula unit (f.u.) and dimer coupling constant are obtained by fitting the temperature dependence of the magnetic susceptibility. It is found that the degree of initial phase disorder is related to the order degree of magnetic sequence in CuO₂ chain. For the un-doped sample, the decoupling of dimers is weak, the magnetic sequence is slightly destroyed, and the streaks in EDP are also very weak, which implies the degree of initial phase disorder in CuO₂ chain is very low. When Zn²⁺ and Ni²⁺ ions are doped, the number of dimers per f.u. decreases, and the intensity of diffraction streaks increases in comparison with the corresponding spots. Furthermore, when the high spin magnetic ions Co³⁺ are doped, the number of holes in Sr₁₄Cu₂₄O₄₁ decreases, the magnetic sequence is destroyed very seriously, and the spots in EDP are extended to streaks almost completely. The phenomenon that the diffraction spots of CuO₂ chain extend to streaks in EDP appears as evidence that the magnetic sequence in the CuO₂ chain is destroyed by doping of Zn, Ni, Co.

Ultrasmall near-monodisperse Ba₂ErF₇ nanocrystals with average crystal size 9.6 nm were synthesized with solvothermal method. The X-ray diffraction (XRD) and transmission electron microscopy (TEM) assays reveal that the as-synthesized Ba₂ErF₇ nanocrystals are of the cubic structure with the cell parameter of 5.943 Å, instead of the reported orthorhombic and tetragonal structure. Two emission bands originated from ²H_11/2/⁴H_3/2 → ⁴I_15/2 and ⁴F_9/2 → ⁴I_15/2 of Er³⁺ can be observed under a 980 nm laser excitation. The magnetic mass susceptibility of the as-synthesized Ba₂ErF₇ nanocrystals reaches 4.293×10⁻⁵ emu g⁻¹ Oe⁻¹.

Porous mullite ceramics were fabricated from pyrolysis of nanometer alumina powders filled silicone resin. At 1573 K, the mixture of nanometer γ-Al₂O₃ and silicone resin can be entirely transformed to mullite in air. The effects of shaping pressure on microstructure and mechanical property were investigated. Increasing shaping pressure leads to decrease in open porosity and average pore size, narrower pore size distribution, and improvement in flexural strength. With a shaping pressure of 43 MPa, nanoporous mullite ceramics with an average pore size of 50 nm can be obtained, showing 33% in open porosity and 42 MPa in flexural strength. The microstructure of porous mullite ceramics consists of dense region and loose region.

The effects of various SiO₂ contents on both the microstructures and properties of Ca-Ba-Al-B-Si-O glass/Al₂O₃ composites were investigated by FTIR, DSC, XRD and SEM. The experimental results show that increasing SiO₂ content in the glass leads to the increase of [SiO₄] units, increases the continuity of glass network, and decreases the trend to crystallization of composites. The shrinkage of samples rises rapid around the glass softening temperature and the final shrinkage of samples decreases with increasing SiO₂ content in the glass. Borosilicate glass/Al₂O₃ composites with 60wt% SiO₂ sintered at 875 °C for 15 min show better properties: a bulk density of 3.10 g·cm⁻³, a porosity of 0.23%, a ɛ _r value of 7.55 and a tan δ value of 0.00053 (measured at 10 MHz) and a well matching with Ag electrodes.

Using high aluminum refractory material as substrate at 1 400 °C, we studied the connections between several oxides such as Fe₂O₃, MnO₂, CuO, and the formation of defects such as coating crack, exfoliation, blistering, erosion, and fading away appeared in the application of high temperature infrared radiation coating. Analyses showed that thermal stress formed during the heating process due to the thermal expansion coefficient differential between the coating and the substrate, and volume effect caused by the crystal transferred when the temperature changed, which resulted in the coating crack and exfoliation. The gas produced by the reactions between components and binder or the components themselves during the heating process caused the coating blistering. The EMPA and XRD analyses show that oxides with low melting point in the penetrating area of the substrate may form eutectic with low melting point and produced thermal defects, which leads to the erosion by penetrating to the substrate. The valent changes of Fe₂O₃ and MnO₂ during the heating process cause the volatilization of the oxides or the pulverization of the coatings, resulting in the coating fades away easily at high temperature for a long time.

Instantaneous creep in face-centered cubic metals, 5N Al (99.999%), 2N Al (99%) and 4N Cu (99.99%) with different grain sizes, was firstly investigated by sudden stress-change experiments at ultralow strain rates $\dot \varepsilon $ ⩽ 10⁻¹⁰ s⁻¹ and temperature T < 0.32 T _m. The experimental results indicate that the observed instantaneous creep is strongly dependent on grain size, the concentration of impurity, and stacking fault energy. Creep in high-purity aluminum, 5N Al, with a very large grain size, d _g > 1600 μm, shows non-viscous behavior, and is controlled by the recovery of dislocations in the boundary of dislocation cells. On the other hand, for 5N Al with a small grain size, d _g=30 μm, and low-purity aluminum, 2N Al, with d _g= 25 μm, creep shows viscous behavior and may be related to ‘low temperature grain boundary sliding’. For high-purity copper, 4N Cu, with d _g= 40 μm and lower stacking fault energy, creep shows a non-viscous behavior, and is controlled by the recovery process of dislocations. For all of the samples, creep shows anelastic behavior.

The macro-plasticity power function constitutive model (MPFCM), the modified macroplasticity power function constitutive model (MMPFCM) and the micro-plasticity constitutive model (MCM) taking the material intrinsic length were established to characterize the microindentation size effects of pure aluminum, respectively. The experimental results indicated MPFCM only determined precisely in the great indentation load. While a modified one named MMPFCM was subsequently established taking account of the parameters variation with the increase of indentation depth. The conventional dimensional analysis method was employed to determine the strength coefficient K and the strain hardening exponent n of this modified model. And then MCM taking account of size effects was proposed based on the Taylor dislocation model. The firstorder steepest gradient descent method was adopted to obtain the material intrinsic length for the geometrically necessary dislocations. The parameters of MCM were identified by using the UMAT subroutine of ABAQUS software. The average absolute relative error of MCM is relatively lower than that of the macro-one. Although the precision of the modified one is also high, the applied scope is limited, only for the microindentation material. In addition, the intrinsic length 5.09 μm of pure aluminum is also obtained based on the strain gradient theory.

Polyvinylpyrrolidone (PVP) nanofibers were processed by magnetic-field-assisted electrospinning (MFAES) technique. Since electric field intensity was one of the most important parameters influencing fiber morphology, the research aimed to study how electric field intensity affects fiber morphology in MFAES technique. The experimental results revealed that the distribution of diameter widened while the average diameter of PVP fibers decreased and the degree of the alignment reduced with the increase of electric field intensity. However, the fibers would be conglutinated together when the electric field intensity was too low. Also, the increase of working distance made the average diameter and the degree of the alignment increase slightly under the same electric field intensity, but the fibers could be partially curved instead of being fully straight if the working distance was too long. It was also indicated that maintaining the electric field intensity at 1 kV/cm with the voltage-distance combinations of 12 kV-12 cm (for 12wt% PVP) and 15 kV-15 cm (for 14wt% PVP) among all other combinations would result in the optimal alignment as well as a narrow size distribution of the fibers.

According to the Fick’s second law of diffusion, six analytical solutions of chloride profile in concrete were studied and discussed with regard to different boundary and initial conditions. In those analytical solutions, the most prevailing error-function solution which is based on semi-infinite assumption is the simple one, but may under-estimate the chloride content in concrete and over-rate the life time prediction of concrete structures. The experimental results show that compared with other solutions, the chloride content in concrete predicted by error-function model is the minimum, and the calculation difference produced by different analytical models should not be ignored. The influence of models on chloride content prediction is more than other environment and material coefficients in some time. In order to get a more realistic prediction model, modification to error-function model is suggested based on analysis and calculation examples concerning the boundary and edge effect.

Effects of calcined coal gangue (CG) aggregates treated by the surface thermal activation on the flowability and strength, and paste-CG aggregate interfaces of the cement-based material were investigated. The experimental results show that the compressive and flexural strength of the cement-based material with the calcined CG aggregates is much higher than that of the material with the natural CG aggregates, but the flowability of the material with calcined CG is significantly reduced with the calcined time. The strength of the material with the calcined CG aggregates only increases little with the calcined time at the same w/c ratio, but is reduced with the calcined time at the same flowability. The CG aggregates calcined by the surface thermal activation obviously overcomes the disadvantages of fully calcined CG.

The feasibility of flue gas desulphurization (FGD) as concrete admixture was studied. A combined concrete admixture of the thermally-treated FGD gypsum and slag powder was explored. The FGD gypsum was roasted at 200 °C for 60 min and then mixed with the slag powder to form FGD gypsum-slag powder combined admixture in which the SO₃ content was 3.5wt%. Cement was partially and equivalently replaced by slag powder alone or FGD gypsum-slag powder, at concentration of 25wt%, 40wt%, and 50wt%, respectively. The setting times, hydration products, total porosity and pore size distributions of the paste were determined. The compressive strength and drying shrinkage of cement mortar and concrete were also tested. The experimental results show that, in the presence of FGD gypsum, the setting times are much slower than those of pastes in the absence of FGD gypsum. The combination of FGD gypsum and slag powder provides synergistic benefits above that of slag powder alone. The addition of FGD gypsum provides benefit by promoting ettringite formation and forms a compact microstructure, increasing the compressive strength and reduces the drying shrinkage of cement mortar and concrete.

Setting time and strength of sulphoaluminate rapid hardening cement (SAC) incorporated in the presence and absence of silica fume (SF) were determined. Combined with the techniques of isothermal calorimeter, XRD and FSEM, the hydration kinetics of the two systems and the effect mechanism of SF on SAC were investigated. The experimental results showed that SF was proved to be beneficial for SAC system, in terms of setting time and late strength gain. Evidence of accelerator effect of silica fume was found during the first 8 hours of hydration. The formation of AFt was accelerated and the microstructure of the hydration products grew denser with incorporation of SF. SF was proved to play the role of dispersion and setting control at early age and had a greater contribution to later strength due to the increment of crystal nucleation point and the pozzolanic activity. Therefore, SF can be used to not only control the hydration kinetics of SAC, but also develop the late strength and improve the microstructure.

The bio-sandstone, which was cemented by microbe cement, was firstly prepared, and then the microstructure evolution process was studied by X-ray computed tomography (X-CT) technique. The experimental results indicate that the microstructure of bio-sandstone becomes dense with the development of age. The evolution of inner structure at different positions is different due to the different contents of microbial induced precipitation calcite. Besides, the increase rate of microbial induced precipitation calcite gradually decreases because of the reduction of microbe absorption content with the decreasing pore size in bio-sandstone.

Based on laboratory tests and field materials evaluation, the inner frictional resistance of SMA skeleton was investigated and then the degradation behaviour of SMA skeleton was characterized for recycling purpose. Inner frictional resistance test was designed to investigate the skeleton characteristics of SMA aggregate mixture. The experimental results indicate that SMA skeleton has much stronger inner frictional resistance than AC skeleton, and coarse aggregates provide main contributions to the inner frictional resistance of SMA skeleton. Crushing test and superpave gyratory compactor (SGC) test were designed to reveal the degradation behaviour of SMA skeleton. To verify the laboratory characterization, field materials were also evaluated. The results indicate that the degradation of SMA skeleton is not random but has fixed internal trend, especially the 4.75mm aggregate plays a key role in the graded aggregates. Based on the testing results, it can be concluded that long-term repeated loading can cause degradation of SMA skeleton. However, the gradation does not keep deteriorating under repeated loading. When the inner frictional resistance is small enough, outside pressure will cause flow deformation of skeleton instead of degradation. Thus, well-designed SMA aggregate mixture is valuable for recycling after long-term in service. And it is important to restore the skeleton, especially the coarse aggregate part.

The applicability of ultrasonic pulse velocity (UPV) method to in-situ monitor setting and hardening process of foamed concrete (FC) was systematically investigated. The UPVs of various FC pastes were automatically and continuously measured by a specially designed ultrasonic monitoring apparatus (UMA). Ultrasonic tests were performed on FC mixtures with different density (300, 500, 800 and 1 000 kg/m³), and different fly ash contents (0%, 20%, 40% and 60%). The influence of curing temperatures (20, 40, 60 and 80°C) was also studied. The experimental results show that three characteristic stages can be clearly identified during the setting process of an arbitrary FC paste: dormant stage, acceleration stage, and deceleration stage. Wet density, fly ash content, and curing temperature have great impact on setting behavior. A stepwise increase of the wet density results in shorter dormant stage and larger final UPV. Hydration reaction rate is obviously promoted with an increase in curing temperature. However, the addition fly ash retards the microstructure formation. To aid in comparing with the ultrasonic results, the consistence spread test and Vicat needle test (VNT) were also conducted. A correlation between ultrasonic and VNT results was also established to evaluate the initial and final setting time of the FC mixtures. Finally, certain ranges of UPV with reasonable widths were suggested for the initial and final setting time, respectively.

The influences of cement type, cement content, and curing time on the unconfined compression strength (UCS) of soil-cement were investigated. The influence of groundwater on UCS of soil-cement was also studied. The experimental results indicate that the soil treated with high grade cement presents a higher UCS. Additionally, the UCS of soil-cement presents linearly increased with the cement content. A logarithm correlation between UCS and curing time presents to forecast the strength development. Compared with the UCS of samples immersed in distilled water, those immersed in groundwater present a higher value.

By taking into consideration of meso-scopic level, four-point bending numerical model of different interfaces was established to analyze the effect of interfacial strength on the bending properties of reinforced concrete beams with the diagrams of crack pattern, the load-step curve and the cumulative AE-loading step curve. The experimental result shows that the peak load, the cracking load and the stiffness before cracking increase with the interfacial strength. Furthermore, the specimen with strong interface presents high brittleness during the failure process, while both bearing capability and ductility could be found in the specimen with moderate interfacial strength.

The synthesis, properties and dispersion mechanism of sulphonated acetone-formaldehyde superplasticizer (SAF) were presented. This superplasticizer was synthesized by the reaction among acetone, formaldehyde, sodium sulfi te and pyrosulfite. The structure and property were respectively characterized by IR and surface tension measurement. Performance of SAF in cement was evaluated by paste flow as well as heat calorimetry. The dispersion mechanism was identifi ed via adsorption and zeta potential measurement. The results show that cement paste mixed with SAF shows good fl uidity. SAF exerts little retarding effect on cement paste and it behaves like a typical polycondensate superplasticizer. The main dispersion mechanism of SAF is attributed to electrostatic repulsion.

The experiments of concrete attacked by sulfate solution under freeze-thaw cycles were investigated. The sulfate solution includes two types of 5% Na₂SO₄ and 5% MgSO₄. Through the experiment, microstructural analyses such as SEM, XRD and TGA measurements were performed on the selected samples after freeze-thaw cycles. The corrosion products of the concrete were distinguished and quantitatively compared by the thermal analysis. Besides, the damage mechanism considering the dynamic modulus of elastically of concrete under the coupling effect was also investigated. The experimental results show that, under the action of freeze-thaw cycles and sulfate attack, the main attack products in concrete are ettringite and gypsum. The corrosion products exposed to MgSO₄ solution are more than those to Na₂SO₄ solution. Furthermore, the content of gypsum in concrete is less than that of ettringite in test, and some of gypsum can be observed only after a certain corrosion extent. It is also shown that MgSO₄ solution has a promoting effect to the damage of concrete under freeze-thaw cycles. Whereas for Na₂SO₄ solution, the damage of concrete has restrained before 300 freeze-thaw cycles, but the sulfate attack accelerates the deterioration process in its further test period.

To investigate the effects of OA on the portland cement using oleic acid (OA) as grinding aid and the effects of OA on the portland cement, we characterized the different perfermances of the cement, discussed the characteristics of properties. The results reveal that the OA can reduce the water requirement of normal consistency. With the content of OA added, setting time was extended. The OA can significantly improve the rheological properties of cement-based materials, while the compressive strength decreases.

The rheological and mechanical properties of high-strength anchorage grouting materials for highway slope were investigated to optimize the mix proportion. The experimental results showed that the optimized mix proportion of high-strength anchorage grouting material (HAGM) was C3 (FA:SP:SF= 1:2:2; AG1:AG2=3:7 and 0.03% FC), which is agreement with the limitation of JCT 986–2005. Moreover, the XRD and FTIR results showed the addition of expansive components was in favor of the formation of ettringite. The intensity of AFt peak of the samples increased with the increasing of hydration time.

A macromer, methoxypolyethylene glycol acrylate (MPEGAA), was synthesized by direct esterification using methoxypolyethylene glycol (MPEG-1200) and acrylic acid (AA) as the main materials. MPEGAA was then used to prepare a polyacrylic acid superplasticizer modified with 2-acrylamido-2-methylpropane sulfonic acid (AMPS). A single-factor test was performed to investigate the effects of the molar ratio of acid to alcohol (n(AA)/n(MPEG)), inhibitor amount, catalyst amount, temperature, and time of esterification on the synthesis of MPEGAA. The experimental results showed that the optimal esterification conditions were as follows: n(AA)/n(MPEG), 3.5:1; amount of hydroquinone (as an inhibitor), 1.2%; amount of para-toluenesulfonic acid (as a catalyst), 5.5%; reaction temperature, 95 °C; and reaction time, 6 h. The AMPS-modified polyacrylic acid superplasticizer prepared under the optimal esterification conditions enabled the achievement and maintenance of high cement dispersibility. At an admixture amount of 0.15%, the cement paste fluidity was initially as high as 300 mm, and then decreased to 315 mm after 1 h and to 290 mm after 2 h.

The aluminum sheet/powders/aluminum sheet sandwich rolling process which was applied to manufacturing precursor of foam aluminum sandwich panel was put forward. The purpose of sandwich rolling was to obtain high densification precursor and bonding of metal face-sheet/powders interface. Compared with mold-compacting, powder densification process and deformation characteristic of interface were studied for the first time in the process of aluminum sheet/powders/aluminum sheet sandwich rolling. The experimental results show powder deformation is a continuous deformation process. Elastic deformation and plastic deformation were produced in powders, thus powders became lamellar structure under rolling pressure. Powders were compacted bonded and atomic force formed among the powders. Metal aluminum sheet exposed fresh metal surface under tensile rolling force. Powders near the interface filled the fresh surface of the metal face sheet and bonded each other.

The multi-component AlCrCuFeMnTi high entropy alloy was prepared using a vacuum arc melting process. Serial annealing processes were subsequently performed at 590 °C, 750 °C, 955 °C and 1 100 °C respectively with a holding time of 4 h at each temperature. The effects of annealing on microstructure, mechanical and electrical properties of as-cast alloy were investigated by using differential thermal analysis (DTA), X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The experimental results show that two C14 hexagonal structures remain unchanged after annealing the as-cast AlCrCuFeMnTi alloy specimens being heated to 1 100 °C. Both annealed and as-cast microstructures show typical cast-dendrite morphology and similar elemental segregation. The hardness of alloys declines as the annealing temperature increases while the strength of as-cast alloy improves obviously by the annealing treatment. The electrical conductivities of annealed and as-cast alloys are influenced by the distribution of interdendrite regions which is rich in Cu element.

Accumulative damage during early stage of fatigue in AISI 321 steel was investigated by eddy current test, atomic force microscopy, X-ray diffraction and transmission electron microscopy. Surface slip, dislocation, and strain-induced martensite were determined as the main damage types. Moreover, damage during the fatigue was found to be increased with the increasing fatigue cycles and load amplitude. The contribution of strain-induced martensite to the total eddy current amplitude (V _max) was enhanced with the increase in its volume fraction. Finally, a linear relationship between V _slip and the height of surface slip was established.

Mechanical properties and microstructures of AZ31 magnesium alloys containing different impurity levels but having the same alloying element content, were investigated at ambient temperature. These AZ31 alloys were produced by semi-continuous casting, wherein the content of impurity was varied systematically. Microstructure observation shows that finer grains are existent in the alloy with lower impurity level. Tensile testing reveals that a reduction of impurity content results in a noticeable increase of the strength and elongation in the alloys in the cast, homogenized and extruded states. As the impurity content decreases from 0.0462wt% to 0.0163wt%, the ultimate tensile strength is evidently enhanced by 62 MPa and the elongation is nearly doubled in the homogenized specimen. The observed property improvement was discussed in terms of the microstructure variation with impurity reduction.

The research on fl uctuation and inhomogeneity of internal stress of aluminum alloy thick plate is theoretical and technological base for stress control technology. By using X-ray diffraction technique and mechanical test method, aluminum alloy with typical fine sub-grains, coarse recrystallized grains, and second phase was analyzed; the interactive mechanical model between grains was built for analysis of variation of internal stress within the local micro structure by imitating the actual distribution of grains. The experimental result shows that the mechanical model can effectively explain the reason for fluctuation of microscopic stress, which also proves that the inhomogeneous distribution of metal organization is the cause for the complex distribution of microscopic stress. The model can well describe stress distribution of thick plate caused by thermal deformation. Besides, it well describes mechanism of stress fluctuation.

The microstructures and mechanical properties of 550 MPa grade lightweight high strength thin-walled H-beam steel were experimentally studied. The experimental results show that the microstructure of the air-cooled H-beam steel sample is consisted of ferrite, pearlite and a small amount of granular bainites as well as fine and dispersive V(C,N) precipitates. The microstructure of the water-cooled steel sample is consisted of ferrite and bainite as well as a small amount of fine pearlites. The microstructure of the water-cooled sample is finer than that of the air-cooled sample with the average intercept size of the surface grains reaching to 3.5 μm. The finish rolling temperature of the thin-walled high strength H-beam steel is in the range of 750 °C–850 °C. The lower the finish rolling temperature and the faster the cooling rate, the finer the ferrite grains, the volume fraction of bainite is increased through water cooling process. Grain refinement strengthening and precipitation strengthening are used as major strengthening means to develop 550 MPa grade lightweight high strength thinwalled H-beam steel. Vanadium partially soluted in the matrix and contributes to the solution strengthening. The 550 MPa grade high-strength thin-walled H-beam steel could be developed by direct air cooling after hot rolling to fully meet the requirements of the target properties.

The nitrided layer on Ti6Al4V substrate was prepared by the plasma nitriding technique. The sample was characterized by X-ray diffraction (XRD), glow discharge optical emission spectroscopy (GDOES), X-ray photoelectron spectroscopy (XPS), and rough-meter. X-ray diffraction analysis reveals that TiN, Ti₂N and Ti phase exist in the nitrided layer subsurface. GDOES analysis shows the thickness of the nitrided layer is about 3 μm. XPS analysis shows that there is higher N, lower Al and lower V in the nitrided layer surface than in the Ti6Al4V surface. Rough-meter analysis results show the roughness of the nitrided layer is greater than that of Ti6Al4V alloy base. The bacteria adherence property of the nitrided layer on Ti6Al4V substrate on the Streptococcus mutans was investigated and compared with that of Ti6Al4V alloy by fluorescence microscope. It shows that the nitrided layer inhibits the bacteria adherence.

The purpose of this study was to investigate the influence of different luting agents on the stress distribution within the crown, abutment and peri-implant bone of implant-supported all-ceramic single crown. A three-dimensional finite element model of an implant-supported single crown for the first premolar of mandible was created by COSMOS 2.85. Resin-modified glass ionomer and two different resin adhesives were used to cement the crown and abutment. Vertical 600 N and horizontal 225 N loads were applied to stimulate the condition of chewing. The stress distributions within the all-ceramic crown, abutment and peri-implant bone were analyzed. The experimental results show that the stress distributions of all-ceramic crown, abutment, implant and peri-implant bone were similar when different luting agents were used. The result of present study indicated that luting agents had no influence on the stress distributions of implant-supported all-ceramic single crown.

Magnetic Fe₃O₄ nanoparticles were synthesized by co-precipitation method and the mercaptopurine (MER) drug-loaded magnetic microspheres were obtained through emulsion cross-linking methods. The efficiency of this approach was evaluated in terms of drug loading content (DLC), encapsulation efficiency (EE) and delivery properties in vitro, determined by high performance liquid chromatograph (HPLC). The microspheres showed good DLC values of 11.8%, as well as good EE values of 79.4%. The in vitro drug release study was carried out in phosphate buffer solution (PBS) simulated body fluid, at 37 °C with pH=7.4. The release profiles showed an initial fast release rate, which decreased as time progressed and about 84 % had been released after 48 h. The experimental results indicated that the prepared magnetic microspheres may be useful for potential applications of MER for magnetically targeted chemotherapy. Key words: mercaptopurine; magnetic microspheres; drug loading content; encapsulation efficiency

The effects of surface modification on montmorillonite (MMT) were illustrated in order to produce the composite material with premium properties. MMT was treated with two coupling agents: glutaraldehyde (GA) and γ-methacryloxy-propyl-trimethoxy silane (KH570). The effects of different coupling agents on MMT and protein interaction were investigated by XRD, FT-IR, TGA, UV-Vis, etc. The results of structure characterization indicated that KH570 modification could change the surface crystal structure of MMT. However, GA reacted with amino groups of Bovine serum albumin (BSA) and the ordered layer structures of MMT were not completely destroyed. Coupling agents could greatly increase the amounts of BSA intercalated and the effect of KH570 is better than that of GA. And, the optimum concentrations of KH570 and GA were 2% and 6%, respectively. The rate of weight loss increased by about 12% after MMT was pretreated with coupling agents. The possible reason is that coupling agent treatment makes the structure of MMT more accessible to protein absorption and helps to stabilize the protein structure. Moreover, the presence of coupling agents can reduce the direct chemical interaction between BSA and MMT, which results in increasing protein desorption.

To explore the preparation of PLGA ceftiofur hydrochlorate lung-targeted microsphere with spray drying process, the preparation technics was optimized by orthogonal experiments. Appearance, particle size, drug-loaded properties and medicine dissolution rate of the microsphere were evaluated. The experimental results show that the prepared PLGA microspheres loaded with ceftiofur hydrochlorate have good appearance, good encapsulate rate and dissolution. The drug loading capacity of ceftiofur-hydrochlorate-loaded PLGA microsphere prepared with spray drying process is 23.06%, i e, when the dosing ratio is 1:3, the encapsulate rate is 92.23% at maximum, and the release percentage of medicine is at 0.5 h. The medicine is released almost completely at 20 h and the accumulated medicine release is 98.12%.

Copper nanoparticles with a size of about 150 nm were prepared in toluene using oleic acid as protecting agent. The nanoparticles were used to prepare conductive Cu ink with a polyurethane binder. Oleic acid was used to prevent the nanoparticles from oxidization and agglomeration. The prepared Cu nanoparticles were characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The resistivity of the copper film on glass substrate that was prepared using Cu nanoparticle ink reached about 1.5 × 10⁻⁴ Ω· cm⁻¹ after it was annealed to 120 °C. Both the nanoparticle ink and the films were characterized by XRD, fourier transform infrared (FT-IR), and the thermogravimetry-differential scanning calorimetry instrument (TGDSC).

High-efficiency blue electrophosphorescent organic light-emitting devices employing MoO₃ used as hole injection layer (HIL) and MoO₃ doped N,N-dicarbazoly-3,5-benzene (mCP) as hole transport layer (HTL) were demonstrated. The blue OLED with the novel anode structure and TAPC used as electron blocking layer show a low turn-on voltage of 2.4 V, a maximum power efficiency of 33.6 lm/W at 3.1 V and 25 lm/W with 1 000 cd/m² at 3.8 V. It is also found that the efficiency of the devices is dependent on the different EBL materials. This is may because of relationship with the charge mobility and the triplet energy level of EBL materials. The device efficiency is determined by the charge balance which plays an important role.