Abstract:The effect of pre-deformation on the age hardening behaviors, tensile properties and precipitate characteristics of an Al-Cu-Mg alloy with a high Cu/Mg atomic ratio during 180℃ artificial ageing was investigated by using transmission electron microscopy (TEM), hardness test and tensile. The results show that room-temperature rolling of Al-Cu-Mg alloys with a thickness reduction of 10%~60% plus a subsequent artificial ageing (P-T6) can result in the strength increase of 32%~69% with elongation ranging from 6% to 13% compared with the conventional heat treatment process (T6). Transmission electron microscopy (TEM) revealed the main precipitates are Ω and θ′ phase in P-T6 condition instead of θ′ phase in T6 condition. Furthermore, the aspect ratio of Ω phase is much bigger than θ′ and the number of Ω phase reaches the total precipitates of 30% ~75%. Compared with θ′ phase, Ω phase processes better precipitation strengthening and thermal stability. Ω phase can form through deformation-induced-precipitating in Al-Cu-Mg alloys, while Ω phase does not precipitate in Mg-free Al-Cu alloys with or without pre-deformation.

Abstract:The effect of Si additions on microstructure, mechanical properties and localized corrosion behaviors of Al-Zn-Mg-Cu alloy was investigated by means of mechanical tensile and exfoliation corrosion testing combined with optical microscopy(OM), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The results show that the strength of the alloys first increases and then decreases with the increase of Si contents, when Si content is 0.040% (mass fraction), the strength of the alloy reaches the peak value; The anisotropic mechanical properties of the alloys first decreases and then increases with the increase of Si contents, when Si content is 0.025%, the alloy has the minimum anisotropy. Concomitant with this increase in Si contents, a transition in fracture mode was observed from predominantly transgranular dimpled rupture to predominantly intergranular dimpled rupture of transverse. Compared with the change of the longitudinal strength of the alloys, the Si contents have a significant effect on the transverse strength of the alloys.

Abstract:AZ91magnesium alloys modified by erbium (Er) and cerium (Ce) (AZErCe)were fabricated by casting into metal mold. The effect of Er and Ce on the microstructure and stress corrosion cracking (SCC) behavior of AZ91 in Cl- containing moist atmosphere was investigated by slow strain rate tensile (SSRT) tests, potentiodynamic polarization analysis, X-ray photoelectron spectroscope (XPS), scanning electron microscope (SEM) and X-ray diffraction (XRD). The results showed that the β-Mg17Al12 phase was transformed from discontinuous network into small island distribution and dispersed homogeneously after the addition of Er and Ce, and the formation of Al3Er and Al11Ce3 intermetallic compounds reduced the volume fraction of β-Mg17Al12 phase.The addition of Er and Ce greatly improved the SCC resistance, because the local corrosion resistance of AZErCe was improved by alleviating the cathodic effect of β-Mg17Al12 phase and improving the compactness of the surface films. As a result, the processes of initiation and expansion of cracks were suppressed and the influence of hydrogen embrittlement on SCC resistance was weakened. The fractography of SCC was changed from brittle cleavage fracture into quasi-cleavage fracture, and the local corrosion at the edge of fracture surfaces was greatly alleviated.

Abstract:The residual stress field of aluminum alloy sub-frame was obtained through its casting process simulation by the software ProCast. Then, the residual stresses were loaded into the finite element model of aluminum alloy sub-frame for the mechanical analysis through the intermediate files as the initial condition. The fatigue life of the sub-frame was analyzed by using HyperMesh,ABAQUS,Fe-Safe and so on.The results showed that the residual stress decreased the working life in the longitudinal, lateral and vertical conditions by 48%, 71.3% and 32.5%, respectively.A bench test on the sub-frame was also performed. The results showed that the fatigue simulation results of residual stress were closer to the results of the bench test, and the performance index of the aluminum sub-frame satisfied the practical requirements.Therefore, the fatigue simulation considering the residual stress provides significance for the vacuum die casting aluminum alloy sub-frame production.

Abstract:In order to study the influence of preformed shapes on the thickness distribution of double-pass incremental forming, based on the double-pass incremental forming of straight-wall part, three double-pass strategies with arc and straight line profile preformed shapes were designed. A finite element method (FEM) model of double-pass incremental forming was then established and experimentally verified. It is found that the double-pass strategy with a curved profile of curvature radius of 80 mm is expected to achieve less thickness reduction,equivalent plastic strain and larger minimum thickness. Additionally, the increased plastic deformation region does not always lead to larger thickness,and the final thickness is mostly related to the actual deformation area during the second pass that depends on the specific design of the preformed shape. Finally, a linear relationship between the curvature radius of the preformed shape and the final thickness distribution is not observed. When the tangential angle(θ) is around 40°,it has the most uniform thickness distribution.

Abstract:To deal with the problem of mesophase microbeads(MCMB) with a poor sinterability in less binder, thermal analysis and SEM were used to study the influence of different types of coal tar pitch on the sinterability of MCMB powder and performance of the graphite bulks. The results demonstrate that coal tar pitch can coat the surface of the MCMB(D50=23 μm) uniformly by dissolving the pitch and blending the mixture, so that the modified MCMB was obtained and the sinterability was improved. The graphite prepared from the modified MCMB was obtained by successive process of isostatic pressing, baking and graphitization, which had a dense and uniform micro-structure. And the flexural strength of the materials was obviously higher than those(22 MPa) made of unmodified MCMBs, and it increased to 27.7 MPa,42.7 MPa and 56.9 MPa,corresponding to the sequence of high softing pitch,modified pitch and middle softing pitch, respectively.

Abstract:Graphene oxide (GO) was prepared via improved Hummers method, and then the GO was functionalized with phenyl isocyanate. Subsequently, functionalized GO (iGO) and 4，4′-diphenylmethane diisocyanate (MDI) were mixed under sonication in dimethylformamide (DMF) solvent to obtain a homogeneous mixture. The mixtures were reacted with polyoxytertramethylene glycol (PTMG) and 1,4-butanediol (BD) in DMF solvent to prepare the iGO/thermoplastic polyurethane (PU) nanocomposites (called GO-TPU), while neat TPU was synthesized under the same conditions for comparison. Characterizations were carried out by XRD, FT-IR, XPS, Raman spectroscopy, SEM and mechanical properties were tested. The results show that the phenyl isocyanate is successfully grafted onto the surface of GO. The tensile strength and elongation at break of nanocomposites are increased first and then decreased with the increase of iGO. Uniform dispersion of iGO is observed in the PU matrix when the content is less than 1 %(mass fraction). It is found that the most significant improvement of the tensile strength (4.26MP) and elongation at break (500 %) is obtained with iGO at 1% content. When compared with neat TPU, the increase is 127.1% and 27.3%, respectively.

Abstract:In this paper, a series of Mn-Mg ferrites with the formula MnxMg1-xFe2O4(x=0.2,0.5,0.8) have been successfully prepared by ultrasonic-assisted ball milling approach. The characterization of the samples has been done using room temperature X-ray diffraction (XRD),transmission electron microscopy (TEM), vibrating sample magnetometer (VSM). The XRD results reveal that the formation of single-phrase ferrite is fully completed after 60 h. The TEM micrograph confirms that the average size of nanoparticles is about 25 nm. The maximum saturation magnetization of 74.22 emu/g is obtained when x=0.5, which decreases with the further Mn doping. The fluorescence measurements and electroconductivity detections reflect the reaction speed and confirm the coupling effect of ultrasonic and ball milling.

Abstract:In this paper, porous carbon nanospheres (PCS) were prepared by carbonization at 1000 ℃ and KOH activation at 750 ℃ of polypyrrole (PPy) nanospheres. Then the post treatment of PCS was carried out by solvothermal reaction with p-Aminothiophenol (PATP) to prepare PATP functionalized PCS with high density (PATP-PCS). The results showed that after functionalization with PATP, low-density porous carbon material turned into high-density functionalized carbon material.The volumetric capacitance of PATP-PCS was up to 183.6 F/cm3 at 0.5 A/g; when the current density increased to 20 A/g, the volumetric capacitance is still 123.14 F/cm3, showing excellent rate performance.After 3 000 cycles of charge and discharge at the current density of 10 A/g, the cycle life is up to 94.7%, indicating a prominent cycle stability.

Abstract:In order to study the rheological properties of magnetorheological gel(MRG) based on silicone, three kinds of MRGs named MRG-30, MRG-50, MRG-70 were prepared based on carbonyl iron powder with a mass fraction of 30%, 50%, 70%, respectively. The steady state rotation shear and dynamic oscillation were systematically tested. The results show that the shear stress varies with the magnetic field and can be classified into three stages: rapid growth, slow growth and saturation. The content of carbonyl iron powder has a great influence on the zero-field viscosity, shear stress and response rate, and MRG-70 has the best magnetorheological effect. The flow characteristic of MRG is consistent with the Herschel-Bulkley function, and the non-Newtonian exponent n satisfies that n<1 with shear thinning property. The critical strain amplitude of linear viscoelastic region increases with the enhancement of the magnetic field, and the storage modulus of the MRG is weakly dependent on the frequency. Normal stress increases with the increase of magnetic field, but the influence of frequency on the normal stress of MRG is very weak.

Abstract:The effects of different contents of mineral admixtures including metakaolin, fly ash and steel slag, on the compressive strength of shale ceramisite concrete were studied systematically and the microstructure and composition were analyzed by SEM and XRD. The results show that the compressive strength of the concrete is the highest when the mass content of the mineral admixtures is about 10%. Then, when two kinds of mineral admixtures are added into the concrete at different ratio, the compressive strength testing shows that the concrete with 10% metakaolin and fly ash (ratio 1∶2) exhibits the best compressive strength (18.1、28.6、35MPa at 3d, 7d, 28d, respectively), which is higher than the concrete without mineral admixture by 417%、267% and 250% at 3d, 7d and 28d, respectively. The main reason is that the addition of metakaolin and fly ash can optimize the microstructure of lightweight aggregate concrete, thus, improving the strength of the concrete.

Abstract:Nitrogen-doped porous carbon (NPC) was successfully prepared by solvent evaporation combined with high temperature thermal polymerization in the present study. The microstructure and element composition of the samples were characterized by SEM, TEM, Thermogravimetric analyzer (TG), N2 adsorption-desorption and X-Ray Photoelectron Spectroscopy (XPS). The results showed that the nitrogen content of the nitrogen-doped porous carbon was 4.2 at% and the specific surface area was as high as 422.0 m2/g higher than that of the nitrogen-free sample(301.1 m2/g), and the specific surface area and pore volume of the samples were obviously increased by nitrogen element doped. Subsequently, the obtained NPC was also characterized with cyclic voltammetry curves, constant current charge discharge curves and AC impedance spectra.The electrochemical results showed that nitrogen doped method could significantly increase the specific capacitance of the sample, reduce the internal resistance of the porous carbon, and greatly improve the electrochemical properties of the carbon material. At the current density of 0.5 A/g, the specific capacitance of N-doped porous carbon was increased from 83.8 F/g to 162.8 F/g, and the internal resistance was reduced from 1.39 Ω to 0.47 Ω.Furthermore, nitrogen-doped porous carbon possessed good rate performance and cyclic stability

Abstract:K2O-Al2O3-SiO2 glass-ceramics were prepared by sintering method. The effects of glass powders with different particle size distribution on the crystallization and microstructure of K2O-Al2O3-SiO2 glass-ceramics were studied, so as to optimize the particle size of K2O-Al2O3-SiO2 glass-ceramics. The results show that the crystallization temperature of glass-ceramics decreases from 913.9 oC to 869.9 oC when the median particle size of glass powder decreases from 38.09 μm to 1.80 μm. Crystallization activation energy also decreased from 320.5 kJ/mol to 234.7 kJ/mol. The crystallized phase of the glass-ceramics are both leucite. When the median particle size of the glass powder is 6.30 μm, the microstructure of the glass-ceramics is more uniform. The glass-ceramics has a density of 2.45 g·cm-3, a flexural strength of 74.93 MPa, and a thermal expansion coefficient of 14.32×10-6 K-1.

Abstract:In order to decrease the material and manufactural cost of the HVOF sprayed cermet coating, to replace the EHC in wider fields, five cermet composite coatings were deposited by HVOF process using the blended Ni60 and WC-10Co4Cr powders with different ratios. Microstructure, properties and sliding wear performance of the Ni60/WC-10Co4Cr coatings as well as electrolytic hard chrome (EHC) coating were investigated. The results showed that all the HVOF sprayed coatings were compact (porosities were less than 1%), their hardness increased from 688.3HV0.3 to 1203.4 HV0.3 and the wear rate decreased from 2.75×10-5 mm3/N·m to 7.29×10-7 mm3/N·m with increasing the WC-10Co4Cr ratio. The wear rates of the HVOF sprayed coatings and their counterparts as well as their frictional coefficient were lower in comparison to the EHC coating, which exhibited excellent sliding wear performance.

Abstract:Due to the long-term corrosion affected by environmental factors, such as sea salt spray, wave-splashing and tidal, a lot of chloride ions in concrete lead to a serious corrosion in marine reinforced concrete structure.As a result, the marine concrete structure is difficult to meet the requirement of 50 years for design service life. In the present work, based on the chloride ion diffusion theory and reliability theory, the effects of structural measures and additional measures on the service life of practical structure in the South China Sea were discussed. The results indicate that the thicker concrete cover thickness can effectively extend the service life of concrete structure. Besides, additional measures also can extend the service life of the structure in tropical marine environment, the most effective method is to use stainless steel instead of ordinary reinforced steel, and however, the high price of stainless steel will limit its application. Compared with other kinds of additional measures,coated with silicone or adding corrosion inhibitor is an effective measure to marine concrete structure. But only one additional measure was used in one dimensional concrete structure that cannot meet the requirement of 50 years of designed service life.

Abstract:In order to be used as ecological river bank protection materials, sintered block should have a high compressive strength and excellent durability to meet the designed service life of hydraulic engineering. Lake sediment is of high plasticity, high drying shrinkage and its final sintered product has low compressive strength. It is therefore necessary to choose appropriate blending material to compensate the shortcomings of lake sediment. In this paper, shale, gangue, coal cinder, brick powder and coal were selected as blender of the lake sediment. Six mixtures were formed, dried and then fired at 925 ℃ to produce bricks. Properties such as drying shrinkage, loss on ignition, bulk density, compressive strength, water absorption, freeze-thaw resistance were determined. Crystal phases and microstructures of the six samples were studied by XRD and SEM. It is found that the samples containing 10% shale or 10% brick powder present the best physical and mechanical properties and excellent durability, which meet the needs of ecological bank protection materials used in hydraulic engineering. Considering the inferior properties of samples with 2% coal, it is not recommended to use coal as internal fuel to produce sintered block for ecological bank protection materials. Finally, sintered blocks from lake sediment were produced in the manufacturing line in factory and were used in ecological river bank protection engineering.

Abstract:Amphiphilic polymer nanoparticles have attracted considerable attention especially as anticancer drug delivery system, since they can enhance bioavailability and reduce side effects of drugs used for chemotherapy. Novel poly (3-hydroxybutyric-co-3-hydroxyvaleric, PHBV)/dextran nanoparticles (PDNPs) drug delivery system was formulated via an original double emulsion (w1/o1/w2) solvent-evaporation method. The mean diameter of PDNPs was 205.0±6.9 nm and their zeta potential was -1.59±0.12 mV by using dynamic light scattering (DLS) detection. PDNPs showed obvious core-shell structure with uniform particle dispersion. Cisplatin, as a model anticancer drug, was loaded to demonstrate the characterizations of the drug delivery system, and its loading did not significantly alter the hydrodynamic diameter and zeta potential of nanoparticles with 19.3±2.9% of drug loading content (DLC).In-vitro drug release profile of cisplatin from cisplatin-loaded PDNPs found that it can be released faster in normal cells (pH=7.4) than cancer cells (pH=5.5) in phosphate buffered saline (PBS), and the release period was more than 7 d,which demonstrated that this drug delivery system was pH-responsive and with excellent slow-release performance. PDNPs displayed no cytotoxicity, and cisplatin-loaded PDNPs exhibited higher killing efficient to cancer cells when compared with normal cells, which indicated this nano-delivery system can kill cancer cells more effectively.Thus, the novel PDNPs drug delivery system can be potentially applied for cancer chemotherapy, which will improve the utilization ratio and reduce side effect of drugsin the cancer chemotherapy.

Abstract:FOF2 is one of the F-box protein family members and its biological function remains unclear. The expression patterns and function of FOF2 in response to salt and cold stress in Arabidopsis were analyzed by real-time quantitative PCR and physiological method. The results showed that FOF2 was highly expressed in root, cauline leaf and silique in Arabidopsis, and its transcriptional level was induced by salt and cold stress. The seed germination and root elongation of FOF2 overexpression lines were hypersensitive to salt stress, while the fof2 mutant showed reduced sensitivity to salt stress compared with wild type. The seed germination of both the FOF2 overexpression lines and fof2 mutant showed no phenotype in response to cold, but their primary root length was shorter or longer than the wild type plant during cold stress, respectively. The salt stress responsive marker genes were down-regulated in FOF2 overexpression lines, but up-regulated in fof2 mutant under salt stress. The cold stress responsive marker genes were up-regulated in FOF2 overexpression lines, but down-regulated in fof2 mutant under cold stress. These results indicate that the FOF2 plays a negative role in salt tolerance, but positive role in cold tolerance in Arabidopsis.

Abstract:In order to establish a MCF-7 cell line with lentivirus-mediated FOXP2 gene silencing and confirm its interference effect, the lentiviral vector (pMAGic7.1-shFOXP2) was constructed by genetic engineering and cotransfected with pVSVG、Δ8.91 into HEK293T cells, which generated the mature lentivirus, viral supernatant was collected and added to MCF-7 cells after 48 h, the mRNA and protein levels of FOXP2 were examined by qPCR and Western blot. Thus, we constructed and identified the lentiviral recombinant vector pMAGic7.1-FOXP2,successfully established a MCF-7 cell line with the interference of FOXP2 expression, as these findings imply a promising strategy for studying FOXP2 functions in breast cancer progression.

Abstract:An efficient method for synthesizing quinoline-2,4-dicarboxylate compounds was developed via a one-pot reaction of catalyzed lewis acid such as cheap and easily obtained AlCl3, CuCl2 and FeCl3 instead of aromatic amines, ethyl glyoxylate and methyl pyruvate. The major products were separated and purified by thin-layer chromatography, and their structures were characterized by FT-IR, 1H NMR, 13C NMR and elemental analysis. The reaction mechanism and the influence of substituents attached to aromatic amine for the reaction were discussed, which will provide a useful reference for molecular design and synthesis of this kind of novel compounds in the future. This method has some advantages such as cheap materials, mild reaction conditions, high atom economy and high yield.

Abstract:Ferulic acid and ferulamides are a class of natural products and derivatives with important biological activity and pharmacological effect. Ferulic acid (1) was synthesized from vanillin through Knoevenagel reaction. Then, a series of ferulamides (2-9) were synthesized through reaction of ferulic acid with amines using DCC as dehydrating agent and DMAP as the catalyst. Compounds 7 and 8 are new compounds. The structures of all synthetic compounds were characterized by NMR、MS and IR spectra. This synthetic method has the advantages of easy availability of starting materials, simple operation and high yield.

Abstract:In order to overcome the burst release of water-soluble drugs, reduce dosing frequency and improve curative effect,two new bond-linking type drug-loaded control-releasing systems: Chitosan-Captopril and Chitosan-Lysyl-Captopril were synthesized from captopril as a model drug and chitosan as carriers. The products were characterized by IR, 1H NMR and MS. The accumulation of drug release rates of Chitosan-Captopril are 59.2% in PBS buffer (pH=7.4) and 78.4% in HCl-KCl buffer (pH=1.2). The accumulation of drug release rates of Chitosan-Lysyl-Captopril are 55.2% in PBS buffer (pH=7.4) and 76.4% in HCl-KCl buffer (pH=1.2). The results show that the two kinds of drug-loaded systems eliminate the phenomenon of burst releasing and have excellent sustained release properties, which are expected to become the ideal control-releasing system of water-soluble drugs.

Abstract:A new porous jute leaf fibres (JLF) sorbent was prepared by soxhlet extraction using chloroform/n-butyl alcohol (1∶1). The JLF sorbent showed a high Cd(II) sorption capacity (198.79 mg/g), due to its porous structure with maximal exposure of functional groups. The sorbent could be well conducted in a wide pH range of 5~8. The removal efficiencies of Cd(II) kept over 86% in the presence of Ca(II) or Mg(II) with concentrations of 60 times higher than Cd(II). Significantly, JLF kept a high sorption efficiency of 97% and structural stability after five cycles. The heavy metals in actual industrial effluent could be efficiently removed, especially, the concentrations of Pb(II), Cd(II) and Cr(VI) decreased below 0.001 mg/L with a low sorbent dosage of 2 g/L. The sorption mainly occurred between metal ions and carboxyl groups, determined by FTIR and XPS methods.

Abstract:Pollution feature and characteristic pollutants in black liquor of red pine chemical pulping were studied to reveal the contribution of lignin in black liquor to pollution load. A UV-visible spectrometry method to determine lignin content in black liquor was established, together with the work curve of the contribution of lignin to the COD content, to explore the contribution of lignin to the COD content.It was found in the cooking process that the concentration of dissolved organic compounds in the black liquor was high with poor biodegradability and complex components. The main organic pollutants include phenolic and organic acid compounds, where the phenolic compounds have up to 84.34% relative concentration. Lignin concentration in black liquor is 65.7 g·L-1 with produced CODcr value as high as 93 640.86 mg·L-1,which accounts for about 51% of the total CODcr load in black liquor. The results show that lignin is the main source of pollution load for black liquor in traditional chemical pulping industry.