Uniaxial tensile tests were carried out in the temperature range of 250–450°C and the strain rate range of 0.7×10⁻³–1.4×10⁻¹ s⁻¹ to evaluate the superplasticity of AZ31 Mg alloy. The threshold stress which characterizes the difficulty for grain boundary sliding was calculated at various temperatures. The surface relieves of superplastically deformed specimens were observed by using a scanning electronic microscope (SEM). Results show that, at the temperature of 400°C and strain rate of 0.7×10⁻³s⁻¹, the strain rate sensitivity exponent, i e, m value reaches 0.47 and the maximum elongation of 362.5% is achieved. Grain boundary sliding (GBS) is the primary deformation mechanism and characterized by a pronounced improvement in the homogeneity with increasing temperatures. A large number of filaments were formed at the end of deformation and integranular cavities were produced with the necking and fracture of filaments. Finally, the model for the formation of intergranular cavities was proposed.

High temperature wear characteristics of a new hot work die steel CH95 doped with a small amount of rare earth (Re) and boron (B) have been investigated and compared with those of conventional die steel H11 at a series of temperatures and loads. Worn surfaces of CH95 steel and H11 steel were analyzed with a scanning electron microscope. It is found that high temperature mechanical properties of CH95 steel are much better than those of H11 steel. The oxide layer formed on the worn surface plays an important role in wear resistance at high temperature. When the load is less than 63 N, the surface oxide layer keeps integrated and the effect of load on high temperature wear is small. When the load is higher than 63 N, the supporting ability of matrix to the oxide layer decreases with the increase of load, which results in an increase of wear rate. Compared with H11 steel, the wear resistance of CH95 steel is much better and the worn surface of CH95 steel is smoother. It is easier for CH95 steel to form a compact and integrated surface oxide layer at high temperature than for H11 steel, which protects the worn surface and reduces wear.

The pressing bonding of steel plate to QTi3.5-3.5 graphite slurry was conducted. Under the conditions of 530°C for the preheat temperature of dies, 45% for the solid fraction of QTi3.5-3.5 graphite slurry, 50 MPa for the pressure and 2 min for the pressing time, the relationship between the preheat temperature of steel plate and interfacial mechanical property of bonding plate was studied. The results show that when the preheat temperature of steel plate is lower than 618°C, the interfacial shear strength of bonding plate increases with the increasing of the preheat temperature of steel plate. When the preheat temperature of steel plate is higher than 618°C, the interfacial shear strength decreases with the increasing of the preheat temperature of steel plate. When the preheat temperature of steel plate is 618°C, the highest interfacial shear strength of bonding plate of 127.8 MPa can be got.

The flow stress at elevated temperatures for magnesium alloy AZ31 was studied using isothermal compression testing. The effect of deformation parameters on the flow stress was studied as well. The kinetics of elevated temperature deformation was expressed by means of some empirical rate equations. The activation parameter has been calculated. A mechanism for the dynamic softening of AZ31 alloy in a hot deformation experiment was identified to be the dynamic recrystallization.

Under the surface peeling of Cu−Fe−P lead frame alloy larger Fe particles were observed by energy dispersive spectroscopy. By using the large strain two-dimension plane strain model and elastic-plastic finite element method, the cause for peeling damage of Cu−Fe−P lead frame alloy was investigated. The results show that when the content of Fe particles is more than 30% at local Fe-rich area the intense stress concentration in the Fe particle would make the Fe particle broken up. The high equivalent stress mutation and the mismatch of equivalent strain 10% at the two sides of interface make it easy to develop to crack and peeling damage on finish rolling. The larger Fe particles in the Cu−Fe−P alloy should be avoided.

The effect of austempering on the mechanical properties of the hot rolled Si−Mn TRIP steels was studied. The mechanism of transformation induced plasticity (TRIP) was discussed through the examination of the microstructure and the mechanical properties of the specimens. The results show that the microstructures of the steels were comprised of polygonal ferrite, granular bainite and a significant amount of stable retained austenite. The specimen exhibits excellent mechanical properties for the TRIP effect. Isothermal holding time for austempering affects the stability of retained austenite. The mechanical properties such as tensile strength, total elongation and strength ductility balance reach their optimal values (776MPa, 33% and 25608 MPa%, respectively) when the specimen is held at 400°C for 25 min.

The reverse martensitic transformation of TiNi alloy wires prestrained in the parent phase was studied. Experimental results show that the reverse transformation of the TiNi alloys prestrained in the parent phase is significantly different from that of the TiNi alloys prestrained in the martensite phase. Three continual peaks appear on the DSC curves of wires with a small prestrain and one high temperature peak appears on the DSC curves of wires with a large prestrain.

Iron aluminide intermetallic coatings were prepared from Fe−Al/Cr₃C₂ cored wires using High Velocity Arc Spraying (HVAS) technology. Erosion and corrosion properties of HVAS sprayed Fe−Al/Cr₃C₂ coatings were investigated. Results show that the erosion at impingement angle of 30° is more than that of 90°. The erosion resistance of coatings was enhanced with the increase of temperature. Coatings had a better erosion resistance than substrates. The erosion changed from ductile behaviors to brittle behaviors above 450°C. At high temperature, the erosion resistances were superior to those at low temperature and room temperature. Coatings had much higher corrosion properties than substrates. The temperature had a little effect on the corrosion resistance of coatings; The corrosion losing of coatings increased slowly with the increase of corrosion time. The HVAS-sprayed Fe−Al/Cr₃C₂ coatings exhibited a high bond strength and hardness.

Hyaluronan is a kind of polysaccharide with high molecule weight. Its structure is relatively complicated and tertiary structure exists among the HA molecules when reaching to a certain solution concentration. FT-IR spectrum has been acquired to show the groups and their ascription in HA. The results of FT-IR spectrum in this essay accords well with that issued by ASTM. As to the newly appearing absorption peaks, sensible explanation has been given. In addition, Ramon spectrum has been employed as a proof for the result of the FT-IR spectrum. Based on the preliminary acknowledge of the functional groups in HA, circular dichroism of the material has also been explored.

The captopril/Chitosan-gelatin net-polymer microspheres (Cap/CGNPMs) were prepared using Chitosan (CS) and gelatin (Gel) by the methods of emulsification. A cross linked reagent alone or in combination with microcrystalline cellulose (MCC) was added in the process of preparation of microspheres to eliminate dose dumping and burst phenomenon of microspheres for the improvement of the therapeutic efficiency and the decrease of the side effects of captopril (Cap). The results indicate that Cap/CGNPMs have a spherical shape, smooth surface morphology and integral inside structure and no adhesive phenomena and good mobility, and the size distribution is mainly from 220 to 280 μm. Researches on the Cap release test in vitro demonstrate that Cap/CGNPMs are of the role of retarding release of Cap compared with Cap ordinary tablets (COT), embedding ratio (ER), drug loading (DL), and swelling ratio (SR), and release behaviors of CGNPMS are influenced by process conditions of preparation such as experimental material ratio (EMR), composition of cross linking reagents. Among these factors, the EMR(1/4), CLR (FOR+TPP) and 0.75% microcrystalline cellulose (MCC) added to the microspheres are the optimal scheme to the preparation of Cap/CGNPMs. The Cap/CGNPMs have a good characteristic of sustained release of drug, and the process of emulsification and cross-linking process is simple and stable. The CGNPMs is probable to be one of an ideal sustained release system for water-soluble drugs.

RGD-containing peptide (K16-GRGDSPC), characterized as non-viral gene vectors, was fabricated to modify the surface of PLGA-[ASP-PEG] matrix, which offered the foundation for gene transfer with porous matrix of gene activated later. Peptide was synthesized and matrix was executed into chips A, B and chip C. Chip C was regarded as control. Chips A and B were reacted with cross-linker. Then chip A was reacted with peptide. MS and HPLC were used to detect the MW and purity of peptide. Sulphur, existing on the surface of biomaterials, was detected by XPS. The purity of un-reacted peptide in residual solution was detected by a spectrophotometer. HPLC shows that the peptide purity was 94%–95%, and MS shows that the MW was 2 741.3307. XPS reveals that the binding energy of sulphur was 164 eV and the ratio of carbon to sulphur (C/S) was 99.746:0.1014 in reacted chip A. The binding energy of sulphur in reacted chip B was 164 eV and 162 eV, C/S was 99.574:0.4255, and there was no sulphur in chip C. Peptide was manufactured and linked to the surface of biomimetic and 3-D matrix, which offered the possibilities for gene transfer and tissue engineering with this new kind of non-viral gene vector.

The impregnation of a special grade PAN precursor fibers was carried out in a 8 wt% KMnO₄ aqueous solution to obtain modified PAN precursor fibers. The effects of modification on the chemical structure and the mechanical properties of precursor fibers thermally stabilized and their resulting carbon fibers were characterized by the combination use of densities, wide-angle X-ray diffraction (WAXD), X-ray photoelectron spectroscopy (XPS), elemental analysis (EA), Fourier transform infrared spectroscopy (FT-IR) and scanning electron microscope (SEM), etc. KMnO₄ as a strong oxidizer can swell, oxidize and corrode the skin of a precursor fiber, and transform C≡N groups to C=N ones, meanwhile, it can decrease the crystal size increase the orientation index and the crystallinity index, furthermore it can increase the densities of modified PAN precursors and resulting thermally stabilized fibers. As a result, the carbon fibers developed from modified PAN fibers show an improvement in tensile strength of 31.25% and an improvement in elongation of 77.78%, but a decrease of 16.52% in Young's modulus.

The interface reaction between the SiC particles (SiCp) and Fe was studied during sintering the SiCp reinforced Fe matrix composites at 1423 K for 1 h. In the composite having 3wt% (weight ratio) SiCp (the 3SiCp/Fe composite), the interface reaction products of Fe₃Si, the carbon precipitates, and Fe₃C or pearlite were generated. Fe₃Si constructs the bright matrix of the reaction zone in the original situation of the SiCp. The carbon precipitates, are randomly embedded in the reaction zone. Fe₃C or pearlite exists at the grain boundaries of the Fe matrix. As increasing the SiCp concentration in the SiCp/Fe composite, the intensity of the interface reaction between SiCp and Fe increases. After the 10SiCp/Fe composite (having 10wt. % SiCp) sintered at 1423 K for 1 h, all of SiCp are decomposed, and replaced by the reaction zone composed of Fe₃Si and the carbon precipitates. No Fe₃C or pearlite was generated during the reaction. The effects of the techniques of oxidizing of SiCp, coating SiCp by interaction with the Cr powder, and alloying the Fe matrix by adding the Cr element on the interface stability of the SiCp/Fe composite system were also investigated, respectively. The oxide membrane and the coating layer on SiCp can inhibit the interface reaction between SiCp and Fe by isolating SiCp from the Fe matrix during sintering. The interface reaction does not occur in the 3 SiCp/Fe-10Cr composite but in the 3 SiCp/Fe-5 Cr composite. In the SiCp/Fe−Cr alloy composites, the interface reaction between SiCp and the Fe−Cr alloys is weaker than, that between SiCp and Fe. The Cr element behaves as a diluent, it causes a reduction in the interface reaction, which is proportional to the amount of the element added.

LiMn₂O₄ thin films were prepared by solution deposition using lithium acetate and manganese acetate as raw materials. The phase constitution and surface morphology were observed by X-ray diffraction and scanning electron microscopy. The electrochemical properties of the thin films were studied by cyclic voltammetry, charge-discharge experiments and impedance spectroscopy in 1 mol·L⁻¹ LiPE₆/EC-DMC solution using lithium metal as both the counter and reference electrodes. The films prepared by this method are of spinel phase. The lattice parameter increases with the annealing temperature and annealing time. The film annealed at 750°C for 30 minutes has the highest capacity of 34.5 μAh·cm⁻²·μm⁻¹, and its capacity loss per cycle is 0.05% after being cycled 100 times.

Fe³⁺-doped nanometer TiO₂ photocatalysts were prepared by sol-gel technique. TiO₂ powders with different Fe³⁺/Ti⁴⁺ molar ratios ranging from 0.05% to 25% were synthesized by calcinating the gels in the temperature range of 200–600°C. The effects of the content of iron ions and calcination temperature on the physical properties of the powders and their photocatalytic activities were examined by the photodecomposition of methyl orange in sunlight. The results show that Fe dopant can decrease the temperature of nanatase-rutile transformation. The ideal photocatalytic property was achieved when the sample with an Fe³⁺/Ti⁴⁺ ratio of 20 at% was calcined at about 300°C for an hour, which is superior to that of commercial Degussa P-25. The optimum microstructure of the Fe-doped TiO₂ for a high photocatalytic activity in sunlight is consisted of nanatase and rutile.

Density function theory (DFT) at the B3LYP/6-311++G(2d)(5D,7F) level of theory was calculated to predict the geometry structures, total energy and net charges of four kinds of dynamic isomer molecules of 2-aminino-5 mercapto-1,3,4-thiadizole (AMT for short). The fact that the atoms in four kinds of dynamic AMT isomer molecules lie in a plane and one kind of AMT is most stable is approved. The results also indicate that the pentagon ring in four kinds of dynamic AMT isomer molecules are aromatics, and the AMTc and Cu corrosion mitigation film produces as a result of the bonds form one by one of the covalent bond of Cu(1) with 7N atom in AMTc and the coordinate bond of Cu with 2S atom in ATMc. The resonant vibration frequencies and IR intensity for the four kinds of dynamic isomer of AMT are also calculated and their IR spectra are shown.

The structure and characteristics of CdTe thin films are closely dependent on the whole deposition process in close-space sublimation (CSS). The physical mechanism of CSS was analyzed and the temperature distribution in CSS system was measured, and the influences of the increasing-temperature process and pressure on the preliminary nucleus creation were studied. The results indicate: the samples deposited at different pressures have a cubical structure of CdTe and the diffraction peaks of CdS and SnO₂: F. As the atmosphere pressure increases, the crystal size of CdTe decreases, the rate of the transparency of the thin film decreases and the absorption side moves towards the short-wave direction. After a 4-minute depositing process with a substrate temperature of 500°C and a source temperature of 620°C, the polycrystalline thin films can be made, so the production of high-quality integrated cell with SnO₂: F/CdS/CdTe/Au structure is hopeful.

The aluminum coating layer was formed on a copper substrate with local strain region by using the electrodeposited method. It was found that the particle shape of the coating deposited on the copper substrate is very sensitive to the strain extent of substrate. The large needle-like aluminum particles were observed on the substrate region with large local strain, indicating that substrate local strain may affect the shape of the deposited particles and promote the nucleation and growth of the deposited particles.

Nanoporous amorphous ZnO films with lamellar structure were electrodeposited on the hydrophilic substrate by utilizing cooperative surface assembly of anionic sodium dodecyl sulfonate (SDS) at a very low concentration and inorganic species Zn(NO₃)₂ under the influence of an electrostatic potential. The deposited films were characterized by X-ray diffraction (XRD) in the range of low-angle and wide-angle, X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and UV-Vis light absorption spectroscopy. The formation mechanism of the films was elementarily discussed.

High density polyethylene filled with conductive carbon black was prepared by conventional melt-mixing method. The effect of unidirectional pressure on the conductivity was studied. Wide angle X-ray diffraction (WAXD) was used to show the influence of pressure on the aggregate structure of the polymer filled with carbon black (CB) fillers. A model on the basis of the formation and destruction of conductive networks was proposed to explain the change in the conductivity with the application of pressure.

A kind of novel compound containing S and Mo elements was synthesized. Its chemical structure was characterized by elemental analysis, IR and NMR. Its anti-wear property and the load-carrying capacity, as an extreme pressure (EP) additive of lubricating oil, were investigated using a four-ball tester. The experimental results show that the additive exhibits a superior anti-wear property and a high load-carrying capacity. The presence of other additives does not interfere with the anti-wear property of the extreme pressure additive. The influences of load and temperature on the property of the additive were examined. The possible mechanism was investigated by means of surface analysis of the tested steel ball specimen, using XPS. The lubrication films formed on the rubbing surface are mainly composed of MoS₂, MoO₃ and MoO₂.

Seven reinforced concrete (RC) beams strengthened in flexure using carbon fiber reinforced polymer (CFRP) sheets subjected to different sustaining loads were tested. The effects of initial load and load history on the ultimate strength of strengthened RC beams were examined by externally bonded CFRP sheets. The main experimental parameters included different levels of sustaining load at the time of strengthening, and load history. Experimental results show that sustaining load levels at the time of strengthening have important influences on the ultimate strength of strengthened RC beams. If the initial load is the same, the ultimate strength of RC beams strengthened with CFRP sheets is almost the same regardless of load history at the time of strengthening.

The semi-continuous seeded emulsion copolymerization of vinyl acetate and butyl acrylate was carried out with hydroxyethyl cellulose as a colloid stabilizer. The morphology of the latex particle and the relationship between the reaction time and the average particle diameter and/or the conversion ratio during the polymerization were investigated. The experimental results show that the morphology of the latex particle possesses the stable steric construction. In the seeded polymerization, the average particle diameter of latex decreased while the conversion ratio increased. At the second term of the emulsion copolymerization (the growth stage of particle size), the latex particle average diameter increased with copolymerization continuously, but the instantaneous conversation ratio was not large, so it was very necessary to properly prolong the time during the holding temperature stage.

The distribution of gold colloids in kaolinite and the interaction between gold and kaolinite surface were investigated by transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). There is strong interaction between the gold particles and the edge surfaces of kaolinite, in low pH solution, the edge surface of kaolinite is positively charged and electrostatic attractive force between colloide gold particles and the positive edge surface of kaolinite would facilitate the adsorption of colloidal gold particles onto the suface. TEM observation shows that the aggregate morphology of gold particles was dominated by particle-particle interaction and gold particles were adsorbed on the edge surface of kaolinite crystals, resulting from the electrostatic attractive force between colloidal gold particles and the positive surfaces of kaolinite. XPS data show that in Au4f electron spectra there are four energy peaks related to gold, 83.8 eV, 85.7 eV, 87.5 eV, and 89.4 eV, respectively, which suggests that in chemical states there are metallic gold and Au bonded to O, similar to the form of Au₂O₃, and composite Au₂O₃ is formed between the edge surface of kaolinite and colloidal gold surface.

The electronic structures of Ca₃Co₂O₆, Na and Ni doped models were studied by the quantum chemical software of Cambride Serial Total Energy Package (CASTEP) that is based on density function theory (DFT) and pseudo-potential. The electronic conductivity, seebeck coefficient, thermal conductivity and figure of merit (Z) were computed. The energy band structure reveals the form of the impurity levels due to the substitutional impurity in semiconductors. Na-doped model shows the character of p-type semiconductor, but Ni-doped model is n-type semiconductor. The calculation results show that the electric conductivity of the doped model is higher than that of the non-doped model, while the Seebeck coefficient and thermal conductivity of the doped model are lower than those of the non-doped one. Because of the great increase of the electric conductivity, Z of Na-doped model is enhanced and thermoelectric properties are improved. On the other hand, as the large decline of Seebeck coefficient, Z of Ni-doped model is less than that of the non-doped model.

Si₃N₄-Si₂N₂O composites were fabricated with amorphous nano-sized silicon nitride powders by the liquid phase sintering (LPS). The Si₂N₂O phase was generated by an in-situ reaction 2Si₃N₄(s)+1.5 O₂(g)=3Si₂N₂O(s)+N₂(g). The content of Si₂N₂O phase up to 60% in the volume was obtained at a sintering temperature of 1650°C and reduced when the sintering temperature increased or decreased, indicating the reaction is reversible. The mass loss, relative density and average grain size increased with increasing the sintering temperature. The average grain size was less than 500 nm when the sintering temperature was below 1700°C. The sintering procedure contains a complex crystallization and a phase transition: amorphous silicon nitride→equiaxial α-Si₃N₄→equiaxial β-Si₃N₄→rod-like Si₂N₂O→needle-like β-Si₃N₄. Small round-shaped β-Si₃N₄ particles were entrapped in the Si₂N₂O grains and a high density of staking faults was situated in the middle of Si₂N₂O grains at a sintering temperature of 1650°C. The toughness increased from 3.5 MPa·m^1/2 at 1600°C to 7.2 MPa·m^1/2 at 1800°C. The hardness was as high as 21.5 GPa (Vickers) at 1600°C.

Cordierite honeycomb ceramics was treated with 1.5 M HNO₃, followed with 1.5 M NaOH at 93°C. The combination of acid treatment with alkali treatment significantly diminished the rebounding of coefficient of thermal expansion (CTE) caused by heat treatment, a phenomenon observed in samples treated solely with acid. Inductively coupled plasma (ICP) analysis results reveal that the alkali treatment preferentially dissolved “free” SiO₂ left in the acid-treated samples, which is considered to be a key factor responsible for the CTE rebounding.

The (1−x) La_0.67Ca_0.33MnO₃(LCMO)+x Cr₂O₃ composites were synthesized by a new liquid phase method. The XRD and SEM measurements reveal that few Cr₂O₃ were soluble in the LCMO structure and the lattice constant of LCMO almost did not change, while most Cr₂O₃ were distributed at the grain boundaries or on surfaces of the LCMO grains. In resistivity versus temperature measurements, a metal-insulator transition was observed when x<0.20. The resistivity increases and the metal-insulator transition temperature decreases with the increasing content of Cr₂O₃. A random resistor network (RRN) model was used to simulate the transport property of the mixture samples. The simulation results agree with the experimental observations. The results show that the method is reasonable for understanding the electronic transport of the composites of the maganite.

Both silica and boron-silica glass materials doped with terbium organic complex were prepared by in situ sol-gel method respectively. XRD and SEM measurements were performed to verify the non-crystalline structure of the glass. The influence of the glass contents on the structure of the glass and the energy level of the doped Tb (III) ions was analyzed by the emission spectra and IR spectra. The effect of B₂O₃ on the photoluminescence properties of rare earth organic complex in silica-based glass was investigated. The IR spectra indicate that the in situ synthesized rare earth complex molecule was confined to the micropores of the host and the vibration of the ligands was frozen. When B₂O₃ was added into the silica host gel, B₂O₃ had little influence on the noncrystalline structure of the glass, and BO₃ triangle, which had a layer structure different from the silica framework, could form. So the silica network became more inhomogenous, and the luminescence of terbium complexes was quenched with the increase of the B₂O₃ amount.

Three novel Ba₅RNiNb₉O₃₀ (R=La, Nd and Sm) ceramics were prepared and characterized in the BaO−R₂O₃−NiO−Nb₂O₅ system. All three compounds are paraelectric phases adopting the filled tetragonal tungsten bronze (TB) structure at room temperature. At 1MHz, Ba₅RNiNb₉O₃₀ ceramics have a high dielectric constants in the range 193–245.3, a low dielectric loss in range 0.0059–0.0087, and the temperature coefficients of the dielectric constant (τ_ε) in the range −1140- −1310×10⁻⁶·°C⁻¹. Their temperature coefficients of the dielectric constant are significantly reduced compared to those of Ba₅RTi₃Ta₇O₃₀ (R=La, Nd, Sm) ceramics.

The tunneling structure of ZnFe_3−xO₄ ferrite was confirmed by high resolution electron microscopy (HREM), non-Ohmic I–V curve and kinetics for α-Fe₂O₃ isothermal phase transformation. The Zn_0.41 Fe_2.59 O₄/α-Fe₂O₃ two-phase polycrystalline has a huge tunneling magnetorsistance (TMR) mainly caused by the tunneling structure. The Zn_0.41 Fe_2.59 O₄ grains are separated by insulating α-Fe₂O₃ thin layer boundaries. The pattern of nanostructure was verified by HREM.

MgTiO₃ precursor was mechanochemically synthesized by high-energy ball milling of MgO and TiO₂. The sintering characteristic of the resulted MgTiO₃ precursor was investigated. The experimental results indicate that particles of both MgO and TiO₂ powders become smaller rapidly, and then the crystalline structures of MgO and TiO₂ change significantly. MgTiO₃ was observed by XRD after 30 hours of ball milling. Strong diffraction peaks of MgTiO₃ were observed after 50 hours of ball milling. HRTEM observation proves that dense MgTiO₃ ceramics with a compact crystalline structure can be sintered from mechanochemically activated MgTiO₃ precursor, the volume density of the resulting ceramic is as high as 95% of the theoretical density, the porosity and average pore diameter of the ceramic are measured as 4.95% and 50 nm respectively, and the transverse strength exceeded 500 MPa.

Using a self-designed temperature testing box in which Xenon-lamp irradiation can be applied, the afterglow feature of SrAl₂O₄: Eu, Dy as a function of temperature has been researched. Two sorts of SrAl₂O₄: Eu, Dy phosphors, namely highest quality commercial one and the self-synthesized one by solid-state reaction process were employed. Results reveal a common phenomenon behaving as phosphorescent sudden extinguishments at a certain low temperature although their threshold temperature value (about223 K) has a slight difference. The general characteristic for the influence of temperature on the afterglow feature presents, compared to the luminescent decay at room temperature (RT), a bigger and faster decrease of phosphorescent brightness with the reduction of temperature, while decay curves still maitain the same pattern composed of a quick decline part and a platform falling part during which the phosphorescent brightness at273 K is only about1/2 as big as that at RT, and at253 K the figure has changed to about1/3. Finally, the reason of previous observed results has been analyzed briefly in theory.

Lattice constants and electronic structures of diluted magnetic semiconductors (In, Mn) As were investigated using the first principles LMTO-ASA band calculation by assuming supercell structures. Three concentrations of the3d impurities were studied (x=1/2, 1/4, 1/8). The effect of varying Mn concentrations on the lattice constants and the electronic structures are shown.

The temperature field during the whole process of SPS sintering TiB₂-BN sample was numerically simulated based on the simplification of the temperature rising process. The result shows that the highest temperature is found in the punch and the heat flows from punch to sample and die in SPS sintering system. In the radial direction, the center temperature of the sample is much higher than the circumference temperature of the sample. In the axial direction, the center temperature of the sample is lower than the border temperature of the sample. The temperature difference in the sample is growing bigger in the sintering process and reaches the maximum at the end of the heating-up process.

Thin films of barium hexaferrite were prepared on fly ash cenosphere particles by the sol-gel method using Fe(NO₃)₃·9H₂O, Ba(NO₃)₂ and citric acid as raw materials. The prepared films were characterized by differential thermal and thermogravimetric analysis (DTA-TG), X-ray diffractions analysis (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDX), X-ray photoelectron spectroscopy (XPS), and vibrating sample magnetometry. The magnetic and structural properties of barium hexaferrite coated cenosphere particles were also studied. The experimental results show that even and continual barium hexaferrite coatings were prepared on fly ash cenospheres, and the magnetic conductivity was imparted to these non-conducting oxide ceramic particles. The low density barium hexaferrite coated cenosphere particles may be utilized for manufacturing microwave absorbing materials.

A whole of 110 specimens divided into 22 groups were tested with varying the volume fraction of steel fibers and the matrix strength of these specimens. The stress-strain behaviors of four types of steel fiber reinforced concrete (SFRC) under uniaxial tension were studied experimentally. When the matrix strength and the fiber content increase, the tensile stress and tensile strain vary differently according to the fiber type. The mechanisms of reinforcing effect for different type of fiber were analyzed and the stress-strain curves of the specimens were plotted. Some experimental factors for stress or strain of SFRC were given. A tensile toughness modulus Re_0.5 was introduced to evaluate the toughness characters of SFRC under uniaxial tension. Moreover, the formula of the tensile stress-strain curve of SFRC was regressed. The theoretical curve and the experimental one fit well, which can be used for references in construction.

The shrinkage behavior of high performance cement concrete made from Portland cement, ultra fine granulated blast furnace slag and pulverized fly ash with addition of superplasticizer at different temperatures from ambient temperature to 120°C under different sealing conditions was investigated by means of length change measurement on cylindrical concrete specimens along with curing age. Results show that drying shrinkage deformations of titled concrete specimens increased rapidly as the curing temperature rose. The development of drying shrinkage deformation can be efficiently controlled with the aid of aluminum tape sealing as compared with the unsealed specimens, especially when the curing temperature is below 60°C, although it will increase dramatically when the curing temperature is elevated to above 90°C. Polymer coating on concrete specimens showed a similar effect on the control of drying shrinkage as the sealing operation with aluminum tape.

The rutting resistance of multilayer asphalt overlay was researched by using laboratory wheel tracking test. The effects of loading level and test temperature on rutting resistance of asphalt overlay structure were evaluated by means of multilayer specimens. In comparison with multilayer tests, standard specimens of various layers were also conducted to evaluate the rutting resistance. Experimental results indicated that the test temperature and applied load have a significant effect on rutting resistance of asphalt concrete. Higher test temperature and heavier applied load resulted in higher rut depths. In addition, the mutilayer wheel tracking test has been demonstrated to be a more reasonable solution in evaluation on rutting resistance of asphatt pavement structure beasuse it reflects the cumulative permanent deformation in all of asphalt layers.

Used as flame retardant of tunnel asphalt pavement, organic bromides produce a large amount of poisons and smoke in construction and flame retardation stage. The alkaline filler was found to replace mineral filler, and the flame-retarded asphalt mixtures were produced. Experimental results show that these asphalt mixtures are smoke restrained; the performances and construction technology of asphalt pavement are not influenced; also the alkaline filler is of low-price. So this kind of flame-retarded asphalt mixtures is suitable for tunnel pavement.

An important problem facing stress-strain response modeling of concrete is the complexity of the compressive strength grades. 21 groups of specimens with different cubic compressive strength (56.3–164.9 MPa) have been numerically analyzed. Using only the compressive strength, a stress-strain response model of different concrete grade was established. The numerical simulation model not only quantitatively reproduces the relationship of uniaxial compressive strength, peak value stress and cubic compressive strength, but realizes the consistence of the ascending branch of stress-strain curves with different strength grades by introducing the correction coefficient k. The results indicate k increases gradually from 0 to approximate 1 with the increase of the compressive strength, corresponding to the transition from the paracurve to straight line branch in stress-strain curves. When k is 0, the model is identical to the Hognestad equation. A good agreement with the experiment data was obtained.

The pozzolanic activity of nano-SiO₂ and silica fume was comparatively studied by X-ray diffraction (XRD), differential scanning calorimetry (DSC), scanning electron microscopy (SEM) and the compressive, bond and bending strengths of hardened paste and concrete were also measured. Results indicate that the compressive strength development of the paste made from Ca (OH)₂ and nano-SiO₂, the reaction rate of Ca (OH)₂ with nano-SiO₂ and the velocity of C−S−H gel formation from Ca(OH)₂ with nano-SiO₂ showed marked increases over those of Ca(OH)₂ with silica fume. Furthermore, the bond strength at the interface between aggregate and hardened cement paste, and the bending strength of concrete incorporated with 3% NS increased more than those with SF, especially at early ages. To sum up, the pozzolanic activity of nano-SiO₂ was much greater than that of silica fume. The results suggest that with a small amount of nano-SiO₂, the Ca(OH)₂ crystal at the interface between hardened cement paste and aggregate at early ages may be effectively absorbed in high performance concrete.

The formation and transformation of ettringite were studied by measuring the ion concentration in liquid phase and analyzing the composition in solid phase. The effects of C₃A, gypsum, lime and C−S−H gel on ettringite formation and transformation were also investigated. The experimental results show that, when gypsum was presented in solid phase, the composition of liquid phase was in favor of ettringite formation. Ettringite formation consisted of three reactions including the formation of [Al(OH)₆]³⁻ octahedral, formation of Ca−Al polyhedra prism in which Ca and Al polyhedra arranged alternately, as well as entrance of SO₄ ²⁻ into the channel of polyhedra. [Al(OH)₆]³⁻ formation, which was the slowest reaction, controlled ettringite formation. The concentration of AlO₂ ⁻ was a main factor that influenced ettringite formation. After gypsum in solid phase was consumed, [SO₄ ²⁻] decreased quickly and [AlO₂ ⁻] increased, and it was possible that ettringite transformed into hydrated monsulfate calcium aluminate (be called M in short) in thermodymanics. The rate of transformation was controlled by diffusion of AlO₂ ⁻.

The volumetric strain was categorized into elastic and plastic parts. The former composed of axial and lateral strains is uniform and determined by Hooke's law; however, the latter consisting of axial and lateral strains is a function of thickness of shear band determined by gradient-dependent plasticity by considering the heterogeneity of quasi-brittle materials. The non-uniform lateral strain due to the fact that shear band was formed in the middle of specimen was averaged within specimen to precisely assess the volumetric strain. Then, the analytical expression for volumetric strain was verified by comparison with two earlier experimental results for concrete and rock. Finally, a detailed parametric study was carried out to investigate effects of constitutive parameters (shear band thickness, elastic and softening moduli) and geometrical size of specimen (height and width of specimen) on the volume dilatancy.

The effect of fly ash on controlling alkali-silica reaction (ASR) in simulated alkali solution was studied. The expansion of mortar bars and the content of Ca (OH)₂ in cement paste cured at 80°C for 91 d were measured. Transmission electron microscopy (TEM) and high-resolution transmission electron microscopy (HRTEM) were employed to study the microstructure of C-S-H. TEM/energy dispersive spectroscopy (EDS) was then used to determine the composition of C-S-H. The pore structure of the paste was analyzed by mercury intrusion porosimetry (MIP). The results show that the contents of fly ash of 30% and 45% can well inhibit ASR. And the content of Ca(OH)₂ decreases with the increase of fly ash. That fly ash reacted with Ca(OH)₂ to produce C-S-H with a low Ca/Si molar ratio could bind more Na⁺ and K⁺ ions, and produce a reduction in the amount of soluble alkali available for ASR. At the same time, the C-S-H produced by pozzolanic reaction converted large pores to smaller ones (gel pores smaller than 10 nm) to densify the pore structure. Perhaps that could inhibit alkali transport to aggregate for ASR.

New approaches were applied to improve the molecular connectivity indices^mχ^gu. The vertex valence is redefined and it was reasonable for hydrogen atom. The distances between vertices were used to propose novel connectivity topological indexes. The vertices and the distances in a molecular graph were taken into account in this definition. The linear regression was used to develop the structural property models. The results indicate that the novel connectivity topological indexes are useful model parameters for Quantitative Structure-Property Relationship (QSPR) analysis.