Abstract:By simulating the space of special environment, the effects of deep cryogenic treatment and thermal-cold cycling treatment on the microstructure and mechanical properties of Ti , TA7，TC4，TC10 titanium alloys were investigated with hardness test，microstructure ，XRD and SEM analysis. The results have shown that deep cryogenic treatment and thermal-cold cycling treatment can improve the microstructure and the mechanical properties. Furthermore, the twinning of titanium is increased through thermal-cold cycling treatment.

Abstract:The present study investigated the quasi-static tensile and fatigue properties of the center-cracked thin and thick aluminum plate single-side repaired with T300 carbon fiber reinforced epoxy composite patches. The repair efficiency of the damaged thin and thick aluminum plates was compared with the tensile and fatigue properties, and the effect of the initial crack length on the properties of the repaired specimens was studied. Then, the tensile fracture mode of the repaired specimens was analyzed. The results have shown that the repair efficiency of the thin aluminum plate is far higher than that of the thick aluminum plate, and the tensile fracture mode of the repaired specimens has two kinds: the crack growth of the aluminum plate in the repaired specimen and the adhesive debond between the patch and the aluminum plate.

Abstract:The flexural stiffness of magnesium alloy is one of the most important assessment indexes for its engineering application. Three-point support method was adopted to investigate the flexural stiffness and Young's modulus of both 2.16mm and 3.66 mm AZ31 and AZ31B magnesium alloy sheet. It indicates that the flexural stiffness and Young's modulus of AZ31 and AZ31B magnesium alloy are almost the same. The flexural stiffness range is from 28.4GPa to 31.1GPa, while the range of Young's modulus is between 41.74 and 45.1GPa. The same experiments were carried out on aluminum alloy and steel samples with the same surface density as that of 3.66mm magnesium alloy sheet, which showed that the magnesium alloy had the largest bending resistance factor. The specific stiffness of AZ31 magnesium alloy was a little higher than that of AZ31B magnesium alloy and 93.2% of that of steel while 20.6% higher than that of aluminum alloy. Therefore, magnesium alloy is a very suitable material for light-weight design. The results have provided a solid experimental support for its wide application and lightweight design.

Abstract:The influences of Cu and Ce on the microstructures and mechanical properties of Al-7Si-0.35Mg alloys were investigated by using the control variables. The alloys underwent the same heat treatment: solution at 505 ℃ for ten hours. Then, the specimens were immediately cooled by water quenching. Finally, the samples were aged at 160 ℃ for 6 hours. The results have shown that Cu and Ce have a significant influence on the improvement of the tensile strength and elongation of the heat treated alloys. After heat treatment, the tensile strength of Al-7Si-0.35Mg alloy can be increased by more than 50% with 3.4%~4.0% Cu, when the Ce content is certain. The tensile strengths of Al-7Si-0.35Mg alloys with 3.6% ~3.8% Cu increase above 390 MPa. Ce has an effective modification on the morphology of eutectic silicon. When the Cu content is certain, the elongations of alloys can be improved from 4.2% to 7.4% with 0.15% Ce. Adding excess Cu and Ce to Al-7Si-0.35Mg alloys, Al9Ce2Cu5Si3 phases emerge. The results have illustrated that Al-7Si-0.35Mg alloys with 3.6% Cu and 0.15% Ce can attain good comprehensive tensile properties.

Abstract:Methods in numerical simulation combined with experiments were used to study the influence of heat-treated condition and process sequences on the springback of 6063 aluminum bent profiles. The results show that the inner and outer materials of profile cross-section during bending process suffer compressive and tensile stress, while the nearby neutral fiber suffers an obvious tensile-compressive stress concentration. The neutral fiber of the whole plastic deformation region has a larger residual tensile stress after unloading. The springback angle of extruded profile increases after artificial aging. With the increase of artificial aging time, the difference of maximum tensile and compressive stress between the inner and outer materials increases, and consequently, the springback angle gradually increases. The curved profile also rebounds after artificial aging and electrophoresis paint, and with the increase of the bending angle, the springback angle increases. The artificial aging time further increases, but the rebound angle of curved profile remains unchanged. The total springback angle is minimum when the extruded profile is first processed by cold bending, and then by artificial aging and electrophoresis painting.

Abstract:Hadfield steels were prepared by adjusting the components of the alloys by adding Cr-V-Ti-RE，Cr-V-Ti，Cr-RE , and V-Ti-Nb-RE, respectively. The investigation was carried out to study the effect of multi-elements alloying on the microstructure and mechanical properties of Hadfield steel through metallographic microscope, scanning electron microscopy, mechanical properties tests and abrasive wear tests. The results have indicated that grains are refined observably, the form and distribution of impurities are improved, and the hardness, impact toughness and wear resistance increase due to multi-elements alloying. Meanwhile, the specimen with Cr-V-Ti-RE elements has optimal comprehensive performances, its hardness and impact toughness, compared with the one without Cr-V-Ti-RE elements, increase by 12.4% and 32.5% respectively, and the wear resistance increases by 13.9%~45.4%. The wear mechanism of Hadfield steel is pit deformation and microscopic cutting under middle and low impact energy, and spalling fatigue under high impact energy.

Abstract:A series of LiAlO2-Li3PO4 solid state lithium ion electrolyte materials were prepared through solid-phase reaction. The influences of experimental operating parameters such as the Molar ratio of materials, and the sintering temperature on the characteristics of the sintered samples were investigated. The results showed that, at 1∶1 stoichiometric ratio of LiAlO2 and Li3PO4, the specimens sintered at 1 000 ℃ consisted of γ-LiAlO2 flakes and γ-Li3PO4 spheres, and the sizes of particles ranged from 0.5 to 1 μm. When the stoichiometric ratio of LiAlO2 and Li3PO4 was 1∶3, the specimens sintered at 1 000 ℃ consisted of mainly Al doped spherical γ-Li3PO4 solid solution and its ionic conductivity was 6.4×10-5 S/cm. It indicated that Al doping could effectively improve the ionic conductivity of Li3PO4 inorganic solid electrolyte. When the Al doped specimens were sintered at 1 100 ℃, the ionic conductivity decreased. The results of cyclic voltammetry showed that the Al doped γ-Li3PO4 solid electrolyte materials had a good electrochemical reversibility in saturated LiNO3 solution, and an electrochemical window of 1.5V was observed.

Abstract:0.7CaTiO3-0.3NdAlO3 (CTNA30) ceramics is a kind of widely used microwave dielectric ceramics with high sintering temperature. In this article, various contents of B2O3 were introduced into CTNA30 to decrease its sintering temperature. Then, the influences of B2O3 content on the sintering temperature, morphology, microstructure and microwave dielectric properties of CTNA30 were investigated with x-ray diffract meter (XRD), environmental scanning electron microscope (ESEM) and vector network analyzer. The results showed that ceramics could be sintered more easily when doped with B2O3. Moreover, the sintering temperature could be decreased to 1 300 ℃ from 1 500 ℃ when doped with 2wt% B2O3 and the corresponding εr reached the maximum 49.99, Qf about 57 862 GHz, which decreased with the increase of doping level, and τf was about 5.39×10-6∕℃

Abstract:By using industrial pseudo-boehmite prepared spherical alumina powder with sol - gel and spray granulation technology, the powder was calcined at different temperatures in the muffle furnace. SEM was used to observe the microstructure of the powder obtained. The phase composition of the powder calcined at different temperatures was probed with XRD. The size distribution of powder was tested by using mastersize. And integrated surface roughness tester was used to test the surface roughness of the workpiece. The results show that the shape of the powder prepared through spray granulation and calcination is spherical. In addition, as the temperature increases gradually, the phase changes from γ-Al2O3 into θ-Al2O3, and then into α-Al2O3. When the calcination temperature is too high, the power will bond with each other. If the time of heat preservation is prolonged, the powder will grow along the dense area. And when the powder has good crystallinity and more uniform size, its polishing performance is much better.

Abstract:A simple template assisted sol-gel method was used to prepare nano-size CoFe2O4 powders with high specific surface area and magnetic properties. The influences of template and heat treated temperatures on the composition, microstructure, specific area, magnetic properties as well as magnetic heating rate were studied through XRD, TEM, BET, VSM and RF heat tests. The results show that adding template helps to obtain pure spinel CoFe2O4 nano-magnetic particles, and with the increase of heat treated temperature, the average grain size of the as-prepared nano-particles increases, reducing its surface area. Without template, the as-prepared nano-particles exhibit serious accumulation. After adding the template, CoFe2O4 particles are the approximate ellipsoid, and connected one by one, similar to a line, and its agglomeration decreases significantly. The average grain size of nano-sized particles obtained when adding template and calcined at 800 ℃ is about 70.0 nm, its specific surface area is 23.7 m2·g-1, its Ms equals to 79.0 emu·g-1, its Mr equals to 37.1 emu·g-1, its coercive force equals to 856.4 G, and its magnetic heating rate is 2.95 ℃·s-1. These values are all significantly higher than that of nano-sized CoFe2O4 particles obtained without template and calcined at 800 ℃. Finally, the formation process of thread-like nano-sized CoFe2O4 particles was discussed.

Abstract:The selection of suitable raw materials is an important method to improve the performance of magnesium phosphate cement. By changing the kind and amount of polymer emulsions added in magnesium phosphate cement, the applicability of polymers was studied. The results show that the viscosity of polymer emulsions is well correlated with the density, fluidity and setting time of modified magnesium phosphate cement; the pH value of polymer emulsions is an important factor affecting the mechanical properties of modified magnesium phosphate cement; the effect of a suitable polymer emulsion and its dosage on the compressive strength of modified magnesium phosphate cement is comparatively less, but it can improve the bond strength and flexural strength of the material and significantly increase its fracture energy. Adding polymer emulsions does not change the type of hydration products. However, the morphology of hydrated products and its dense degree are significantly affected.

Abstract:The effect of biosurfactantrhamnolipid alone and its combination with cation chemical surfactant cetyltrimethyl ammonium bromide (CTAB) on sludge dewaterability was investigated by determining the water content of dewatered cakes and capillary suction time (CST). When the rhamnolipid dose was 0.01 g·g-1 , the water content of sludge after centrifugation was lower by about 2.4% compared with raw sludge, while the water content of filtered sludge cake was lower by about 10.8%; but the value of CST increased from 27.3 s to 48.8 s. The results showed that the addition of the biosurfactantrhamnolipid could significantly promote the dewatering of sludge, but would slow down the dewatering rate of activated sludge. Compared with rhamnolipid or CTAB alone, the combination of rhamnolipid and CTAB (the combination proportion was 1∶1, 1∶2 or 1∶3) could not only decrease the water content of dewatered sludge cakes, but also improve the dewatering rate of activated sludge.

Abstract:The acclimation of microorganisms responsible for phosphorus removal consisting of PAO and DPB was investigated by using two (enhanced biological phosphorus removal) EBPR reactors running anaerobic/aerobic (RAO) and anaerobic/anoxic (RAA) respectively to demonstrate the applicability of EBPR to wastewater treatment at low temperature. The results have shown that, at the temperature of 8~11 ℃, phosphorus removal microorganisms (Accumulibacter) have been completely enriched in both anaerobic/aerobic and anaerobic/anoxic reactors after 40 and 80 days of operation, respectively. It has been found that the capacities of phosphorus release and uptake by PAO are higher than that by DPB, presenting the ratios of phosphorus release to MLVSS and phosphorus uptake to MLVSS of 27.7 mg P/g MLVSS, 35.2 mg P/g MLVSS in RAO and 17.4 mg P/g MLVSS, 23.1 mg P/g MLVSS in RAA, respectively. Moreover, DPB can immediately use oxygen as the electron acceptor for uptake phosphorus when given an aerobic condition, while PAO does not rapidly use nitrate as the electron acceptor when given an anoxic environment with the phosphorus uptake per MLVSS of 6.9 mg P/g MLVSS only accounting for 19.6% of that in aerobic condition. Fluorescence in situ hybridization (FISH) analyses has shown that PAO (79.3% of all bacteria) and DPB (61.6% of all bacteria) are dominant in their respective reactors, significantly greater than that in seed sludge (9.3% of all bacteria), which also demonstrates that microorganisms responsible for phosphorus removal have been effectively enriched in the two EBPR systems proposed.

Abstract:Activated carbon (AC) was modified with microwave irradiation at 600, 700 and 800 ℃respectively. Specific surface area and pore size analyzer, Boehm titration and Fourier transformed infrared spectroscopy were used to measure the physicochemical properties of the activated carbons. Fixed-bed adsorption experiments were conducted at 10 ℃ with methanol as the adsorbate. The research shows that, after microwave modification, the specific surface area and total pore volume of activated carbons decrease slightly, but the micropore specific surface area increases remarkably. With the rise of temperature, large numbers of surface acidic functional groups of activated carbons resolve and surface basic functional groups are formed gradually. Both the Langmuir equation and Freundlich equation can well describe the adsorption of methanol on the activated carbons. Pseudo-second-order kinetic equation describes the dynamic adsorption process of methanol most suitably, which illustrates that methanol adsorption is a physical and chemical composite adsorption process, and adsorption is affected by the surface functional groups of the activated carbons. The fitting result of intra-particle diffusion model is divided into three linear stages: surface adsorption stage, asymptotic adsorption stage and adsorption equilibrium stage. After microwave modification, the adsorption energy of activated carbons for methanol increases, and the adsorption energy is proportional to the contents of surface nitrogen groups of the activated carbon.

Abstract:The indices (correlation coefficient > 0.51), which are related to the Chang-Zhu-Tan section of the Xiangjiang River, were selected by using the analytic hierarchy process. The weight values of these indices were given according to their importance. The water resource development potential of the Chang-Zhu-Tan section of the Xiangjiang River was calculated by establishing Gray beam function and Grey matrix. The results have shown that the water resource development potential can be evaluated with the Multi-level Grey theory. The water resource development potential in the Chang-Zhu-Tan Urban Agglomeration is 2.983, which belongs to the second-highest range [2.500, 3.250]. This indicates that the water resources of the Chang-Zhu-Tan section of the Xiangjiang River are higher within a certain time range.

Abstract:Benzofurans compound 2-(3',4'-dihydroxyphenyl)-3-methoxy carbonyl-5-methoxy carbonyl vinyl-7-hydroxy-2,3-dihydrobenzofuran (1) and benzodioxanes compound 2-(3',4'- dihydroxyphenyl)-3-methoxy carbonyl-6-methoxy carbonyl vinyl-2,3-dihydro-1,4-benzodioxane (2) were synthesized from caffeic acid through esterification and biomimetic oxidative coupling reactions. Moreover, a series of benzofuranneolignan compounds 3~7 and benzodioxaneneolignan compounds 8~10 were synthesized from compounds 1 and 2 respectively through acetylation, DDQ oxydehydrogenation, Pd/C catalytic hydrogenation, lithium aluminium hydride reduction and deacetylation in alkaline condition. All of these synthesized compounds were confirmed with MS, IR, 1H NMR and 13 C NMR spectra. Among them, 5~7,9 and 10 are new compounds. 8 is the natural product isoamericanol A. The biological activities of benzofuranneolignan compounds 1, 3~5 against five human cancer cell lines were evaluated in the standard MTT method, and the results have shown that compounds1, 3, 4 and 5 exhibit good inhibitory effect on leukemia cells (HL-60),lung carcinoma cell (A-549), breast cancer cell (MCF-7), colon cancer cell (SW-480), and hepatoma carcinoma cell (SMMC-7721).

Abstract:The polypyrrole(PPy) films were synthesized in pyrrole and NaClO4 aqueous or acetonitrile solution on stainless steel by cyclic voltammetry. The morphology of PPy films was observed by scanning electron microscopy, the conductivity was measured by four-probe and its corrosion protection properties were investigated by potentiodynamic polarization curves and electrochemical impedance spectroscopy in 1 mol/L H2SO4. The morphology of two kinds of PPy films showed spherical type, but that prepared in water had more nodules. The conductivity of the PPy prepared in acetonitrile was higher than that in water, and aslo provided better protection properties for stainless steel. The donor number of acetonitrile was smaller than that of water, and acetonitrile had little reaction with polymer intermediates which was difficult to end the chain reactions. As a result, PPy film prepared in acetonitrile possessed with long conjugacy-length, small structure defects, high conductivity and better corrosion-resistance.

Abstract:In the presence of cesium hydroxide, the reaction of O,O-diethylphosphonate with alkynylselenides at room temperature does not provide the expected additional product by using dimethyl formamide (DMF) as the solvent, but rather causes the cleavage of Se-Csp bond and gives the corresponding terminal alkynes and Se-aryl phosphoroselenoates in 89~95% yields. The influence of substituent at the alkynes and selenium atom on the reaction was investigated, and the results showed that the reaction was not sensitive to the electronic nature. The reaction mechanism was that O,O-diethylphosphonate reacted with cesium hydroxide to produce (EtO)2P-(O)Cs+, which underwent nucleophilic attacks on alkynylselenides to produce Se-aryl phosphoroselenoates and RC≡C-Cs+. The latter was hydrolyzed in the presence of water to form terminal alkynes and catalyst cesium hydroxide. The method could provide a new and simple path for the cleavage of Se-CsP.

Abstract:To measure the corrosion resistance of stainless steel and to study the corrosion protection mechanism of polypyrrole film (PPy) on stainless steel, measurement methods such as cyclic voltammetry, electrochemical impedance spectroscopy（EIS） and open circuit potential time curve were used to detect the electrochemical behavior of stainless steel/PPy in Sodium Dodecyl Sulfate（SDBS）and NaCl solution. Then, a reasonable equivalent circuit was established to explain the EIS. The result indicated that reasonable equivalent circuit could isolate the corrosion resistance of stainless steel and the redox resistance of PPy, which perfectly explained the impedance behavior of stainless steel/PPy in solution. In 3.5%NaCl solution, the PPy has good corrosion inhibition effect on stainless steel. The electrochemical reaction between stainless steel and PPy film could release DBS- and insoluble substance to inhibit metal corrosion, which would be the corrosion resistance mechanism of polypyrrole film (PPy) on stainless steel.

Abstract:In this paper, we investigated some properties of the closed lattices and gave their characterizations. The relationship between the Locale and the closed lattice was investigated. It is proved that the Cartesian product of the close lattice is still closed lattice. Moreover, we obtained the result that the closed lattice under a surjective map preserving arbitrary sups is still the closed lattice. Finally, we studied the property of the image of the closed lattice under the closure operator.

Abstract:This paper proposed a feasible conjugate gradient algorithm for solving large-scale nonnegative constrained optimization problems by employing the subspace-projection strategy and the Liu-Storey (LS) conjugate gradient method and established its global convergence. Experimental result shows that the proposed algorithm is efficient.

Abstract:In this paper, we first defined the very weak solutions to degenerate elliptic equations in a bounded smooth domain with a flat boundary piece. Then, we obtained the existence and uniqueness to such very weak solutions by applying variational method and maximum principle of degenerate elliptic equations.