Abstract:The effect of gas nitriding and subsequent ageing on the microstructure and properties of 2Cr13 steel was investigated using X-ray diffractometer, scanning electron microscope, transmission electron microscope, microhardness tester, wear tester, bend test and immersion corrosion test. It was found that with the increase of nitriding temperature and time, both of the thickness of nitrided layers and surface porous layer increased. The diffusion layers of the sample nitrided at 500 ℃ mainly consisted of martensite, a large amount of dislocation and dislocation cell structure, as well as a large amount of CrN nano-precipitates. The CrN nano-precipitates dispersedly distributed in the interior of grains and at the boundaries of dislocation cells, and the CrN nano-precipitates at the boundaries of dislocation cell were denser and larger than those in the grain interior. Further, a large amount of ε-Fe2-3 N or (Cr,Fe)2N were precipitated in the grain boundaries of lath martensite. When the nitriding temperature increased up to 550 ℃, the martensite recovered itself, and the CrN precipitates lined up to form CrN lamellas. The microstructure of the diffusion layers was also transformed into the lamellar pearlite that consists of the α-Fe matrix and CrN phase. The surface hardness of nitrided samples first increased and then declined with the increase of nitriding temperature, where the peak hardness (1 274 HV0.5) reached at 500 ℃. On the other hand, the hardness of diffusion layers formed between 450 ℃ and 500 ℃ was greater than 1 300 HV0.1, and obviously decreased with the nitriding temperature. The wear resistance and corrosion resistance of 2Cr13 steel were improved after nitriding at 500 ℃ for 5 h, but the bend toughness decreased. No matter water cooling or air cooling or subsequent tempering of 420 ℃ for 2 h was applied, the variance of the microstructure at the diffusion layers of 2Cr13 steel nitrided at 500 ℃ was limited, and their hardness was also not changed obviously and was still greater than 1 000 HV0.1.

Abstract:Compression test of ZGMn13Cr2 Hadfield steel was carried out by Gleeble-3500 thermal simulator at the deformation temperature of 298 K under a constant loading strain rate of 0.1 s-1 and with the compressive deformation of 5%, 30%, and 50%, respectively. The effects of compressive deformations on the microstructure evolution and work hardening mechanism of ZGMn13Cr2 Hadfield steel were analyzed by optical microscope, vickers micro-hardness machine, transmission electron microscopy and X-ray diffraction. The test results show that a large number of deformation bands appeared in the grains of compressed high manganese steels. The deformation bands intersected, tangled and isolated with each other. A great deal of high density dislocation was entangled into dislocation cells or dislocation walls with the compression amount of 5%. Deformation twins appeared in the matrix when the compression amount was 30%. With the increasing of compressive deformation, the amount and volume fraction of the twins increased gradually. When the compression amount was 50%, the micro-hardness of water-quenched high manganese steel increased by 125% compared with the initial state, showing HV560.8. Meanwhile, XRD results show that the matrix structure remained austenite and with a bit of carbide, but no deformation-induced martensites were founded in these deformed samples. With the increasing of compressive deformation, work hardening mechanisms of Hadfield steel changed from dislocation strengthening into mainly relying on deformation twin supplemented by dislocation and stacking fault mechanisms.

Abstract:Repetitive upsetting and extrusion (RUE) was firstly carried out on 2A66 Al-Li alloy. Electron back-scatter diffraction (EBSD), transmission electron microscopy (TEM), scan electron microscopy (SEM), and room temperature tensile testing were then performed to investigate the microstructure characteristics and mechanical properties of 2A66 Al-Li alloy. The results showed that RUE was effective in refining the microstructure of 2A66 Al-Li alloy. With the increase of RUE pass numbers, high density dislocations in 2A66 Al-Li alloy gradually transformed to dislocation walls and subgrain boundaries, distribution of large second phase (θ′) became more homogenous, and a part of β′ dispersion dissolved into the aluminum-lithium alloy matrix. After RUE processing, the ductility improved greatly with a modest reduction in strengthening, as the toughening of the alloy was mainly attributed to the change of dislocation, the homogeneity and fragment of θ′ phase, and the dissolution of β′ dispersion.

Abstract:The effects of rolling mode (conventional rolling and high strain-rate rolling in a single pass) on bio-corrosion behavior of magnesium alloys (ZK60, Mg-4Zn-0.3Ca, Mg-4Zn and pure Mg) were investigated by optical microscope (OM), scanning electron microscope (SEM), mass loss of immersion testing and tensile testing. The results showed that magnesium alloy prepared by high strain-rate rolling exhibited lower average corrosion rate and reduced slightly in ultimate tensile strength, compared with the counterpart prepared by conventional rolling. Meanwhile, better corrosion resistance was also exhibited, which could be attributed to the grain refinement, higher DRX extent, fewer twins, and relatively coarse remained second phases. The as-rolled alloys also exhibited a uniform filiform corrosion due to the lower fraction and finer size of the second phase.

Abstract:The effect of water toughening treatment on mechanical properties of high manganese steel bonded TiC hard alloy was systemically investigated, and the microstructure and element distribution of the alloy before and after the treatment were also evaluated by SEM and EDS in order to understand the internal relationship with its properties. The bending strength and impact toughness of high manganese steel bonded TiC hard alloy by normal vacuum sintering were increased by 154.6% and 125.3%, but those of low pressure sintering specimens were increased by 61.81% and 45.38%, and 65.59% and 32.90% for vacuum and low pressure sintering specimens, respectively. The results revealed that water toughening treatment could effectively improve the bending strength and impact toughness of the steel bond hard alloy. As-sintered steel-bonded TiC hard alloy should be heating treated by water toughening treatment or high temperature homogenizing treatment for better mechanical properties.

Abstract:Taking poly (vinyl chloride) (PAH) as a template agent, (NH4)2CO3 as a precipitant, cerium carbonate crystals of special morphology were synthesized by using a liquid phase method. The morphology of cerium carbonate with different reaction time and structure of cerium carbonate crystals were characterized by the techniques of laser confocal microscope, scanning electron microscope, Fourier transform infrared spectroscopy and X-ray diffraction. The results show that under the action of PAH, the morphology of cerium carbonate was gradually transformed into hexagonal flake from initial rodlike, and this process was related with the orientation adsorption of PAH to the different crystal faces of cerium carbonate. Meanwhile, the electrostatic adsorption process of PAH and crystal faces of the cerium carbonate materials were also simulated by material studio software, thus revealing the formation mechanism of PAH template regulated cerium carbonate morphology.

Abstract:Bi2O3-B2O3-SiO2 sealing glass was firstly prepared by melting method. The effect of ZrO2 content on the phase composition, softening temperature, thermal analysis, acid resistance, microstructure and mechanical properties of sealing glass was studied by infrared spectra, X-ray diffraction analysis, thermal expansion coefficient testing, scanning electron microscopy and three-point bending testing. The results showed that when the ZrO2 content was less than 4%, crystal did not occurred in the glass sample, as it is known that when the ZrO2 content was equal to or more than 4%, ZrO2 crystal and α-Bi2O3 was found in the glass sample. \[BO3\], \[BO4\], \[BiO3\], \[SiO4\] and \[ZrO4\] groups are the main components of the sealing glass. When the ZrO2 content was less than 3% and with the increased amount of ZrO2, the softening temperature, transition temperature, acid resistance and bending strength of the glass sample increased, while its thermal expansion coefficient decreased. Meanwhile, when the ZrO2 content was 3%, softening temperature and transition temperature of the glass sample reached the maximum value of 510 ℃ and 562 ℃, respectively, while the thermal expansion coefficient reached the minimum value of 6.92×10-6 K-1, and the bending strength also reached the maximum value of 49 MPa. With the increase of ZrO2 content, the softening temperature, transition temperature, acid resistance and bending strength of the glass sample decreased, but its expansion coefficient increased.

Abstract:In order to avoid the “water flooding”, the excess water generating in PEM fuel cell should be drained timely. In this study, an experiment model was applied to analyze the path of water flow corresponding to the flow resistances based on the “flooding” between catalyst layer (CL) and gas diffusion layer (GDL). Narrow apertures in the largest pores of carbon paper gas diffusion layer are the primary resistance to liquid water penetration. After sufficient hydrostatic pressure is applied, water penetrates the limiting aperture and flows through the pore reaching the GDL surface. For the carbon paper GDL material, the pressure(~1 kPa)required for water to flow through the pores is much less than the pressure (~6 kPa) to penetrate the limiting aperture of the pores. Adding micro-porous layer (MPL) can obviously increase water penetrate resistance. The content of Teflon in the MPL has little effect on the water penetration pressure. It is helpful to promote the water management in fuel cell by setting pilot holes on the carbon paper GDL material.

Abstract:Lake silt and solidified lake silt were used as the main raw materials to prepare fired brick samples employing the vacuum plastic extrusion in a laboratory scale study. Raw material properties tests showed that the addition of a small amount of solidified agent had limited influence on the plasticity index, oxide composition and mineral composition, but had some influence on the formability. Linear drying shrinkage, water absorption, bulk density, compressive strength, thermal conductivity and freeze-thaw resistance of two kinds of brick samples were tested. The test results showed that linear drying shrinkage of solidified silt brick samples with 90% solidified silt and 10% cinder was 5.42%, water absorption was 18.2% and compressive strength was 15.8 MPa. The overall performance of the fired brick samples made of solidified silt was slightly worse than that of the fired brick samples made of lake silt. In addition, SEM and MIP were used to examine the microstructural properties of brick samples, and the results demonstrated that the micro-structure of bricks made of solidified lake silt was more loose, and the porosity was higher than those of the bricks made of lake silt at the same dosage of cinder, which play an important role in the performance of the brick samples such as compressive strength and water absorption. Meanwhile, the thermal conductivity of the former was slightly lower, and freeze-thaw resistances of the both bricks were almost similar.

Abstract:The effect of mineral admixtures on sulfate attack for mortars subjected to electrical pulse was investigated by the appearance observation and strength measurement on the mortars with and without mineral admixtures under electrical pulse and immersion. The microstructures of the damaged specimens were analyzed by using scanning electron microscopy and energy dispersive spectrometer. The results showed that electrical pulse accelerated the penetration of the external sulfate ions into the mortars, and the sulfates then reacted with the cement hydration products to form massive ettringites. As a consequence, the specimens displayed significant cracking and spalling as well as strength reduction within a short period. Mineral admixtures improve the sulfate resistance performance of the mortars, and the improvement is increased with the increase of the amount of the admixtures. However, the mortars blended with mineral admixtures were still subjected to the dramatic sulfate corrosion under electrical pulse. The above findings indicate electrical pulse the accelerated sulfate attack, and also provide a new idea in rapidly evaluating the sulfate resistance of cement-based materials.

Abstract:The interaction effects between a single circular interfacial crack and screw dislocation located inside the matrix were investigated for 1D hexagonal quasicrystal. Through applying the complex potential method, the closed form solutions of this problem were obtained. The degradation results are consistent with the conclusions in previous literature. The stress intensity factor at the crack tip was also derived. The results show that the stress intensity factor decreases with the increase of the distance between the dislocation and interfacial crack. With the increase of the opening angle of the circular interfacial crack, the stress intensity factor increases firstly and then decreases.

Abstract:A simple and efficient synthesis of β-ketophosphonates was described. The hydrolysis reactions of alkynylphosphonates in the presence of sulphuric acid (3.5 mmol) as a catalyst in the recyclable ionic liquid N·(HSO4)2 afforded the desired β-ketophosphonates in excellent yields（98%）. This method has the advantages of metal-free and tolerance of multifunctional groups. Synthesized compound 2p has not been reported.

Abstract:A series of transparent UV-curable nonionic polyurethane (PU) hydrogel were prepared by the prepolymerization of polyethylene glycol 2000(PEG-2000), isophorone diisocyanate (IPDI), 2-hydroxyethyl acrylate (HEA), 1,4-butanediol (BDO) and glycerol (GLY). The influence of the proportion of BDO to GLY on swelling properties and tensile properties of PU hydrogel was studied. The effects of temperature and ionic strength on the swelling ratio (SR) of PU hydrogel were also investigated. The results indicated that when nBDO/nGLY=1, the tensile strength of PU hydrogel dry film reached 1.46 MPa, elongation was 87%, and SR was 370% in the deionized water at 20 ℃. Meanwhile, PU hydrogel showed strong temperature sensitivity and good stability to ionic strength. The release of the gentamycin sulfate from the swelling hydrogel in PBS buffer solution was eventually investigated to verify whether the obtained hydrogel can be used in drug delivery.

Abstract:4-Methylumbelliferone (4-methyl-7-hydroxycoumarin, 1) is a coumarins natural product with important biological activity. Firstly, 4-methylumbelliferone (1) was synthesized from resorcinol and ethyl acetoacetate by Pechmann reaction. Nine coumarin derivatives (2~10) were then synthesized through Mannich reaction, acetylation, Fries rearrangement, O-methylation, Baeyer-Villiger oxidation, O-prenylation and Claisen rearrangement from 4-methylumbelliferone (1). Their inhibitory activities on human cervical carcinoma Hela cells were evaluated in vitro. The biological testing results showed that 4-methyl-5-prenyl-8-hydroxy-7-methoxycoumarin (10, IC50 = 28.58 μmol/L) displayed stronger activity than the positive control drug cis-Platin (IC50 = 41.25 μmol/L), which is worthy of further study.

Abstract:Porous spherical carbon was prepared by using petal-spherical polyaniline (PANI) as a precursor through carbonization and activation with KOH. The morphology, structure and surface chemical composition were analyzed by scanning electron microscopy (SEM), transmission electron microscopy (TEM), N2 adsorption-desorption, X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The influence of carbonization temperature on electrochemical performance of porous carbon was also investigated. For the obtained spherical particle with the small diameter of about 2 μm, large specific surface area was up to 2 496.6 m2/g, and some optimized porous was also distributed at the carbonization temperature of 750 ℃ and activation temperature 850 ℃. Meanwhile, the synthesized porous carbon exhibited a high specific capacitance up to 247 F/g at 0.5 A/g, and 182 F/g even at a high current density of 20 A/g, which indicated good rate capability. Moreover, 102% of the initial specific capacitance was retained after 1 000 cycles at a high current density of 10 A/g.

Abstract:The variations of anti-aging indices of acrylic polyurethane coating with the accelerated aging experimental time were investigated through xenon lamp indoor accelerated aging test, and the mathematical models between the anti-aging indices and accelerated time were also established preliminarily according to the detection of gloss, color difference and micro-morphology. The test results showed that the relationship between the mathematical models of the gloss and the gloss loss rate with the accelerated experimental time were approximately an exponential function, while the relationship between the mathematical model of the color difference with the accelerated experimental time was approximately a power function. Moreover, the experimental data were well fitted based on the mathematical models in order to get the mathematical relationships, and the correlation coefficients were above 0.99.

Abstract:The grafting copolymer (PLA-g-CDA) was prepared by using Sn(Oct)2 as catalyst and grafting meso-lactide onto the cellulose diacetate in the vacuum melting environment. The copolymer was characterized using FTIR, DSC and stretching test. The effects of feed weight ratio, catalyst content, reaction temperature, reaction time and reaction atmosphere on the monomer conversion and grafting ratio were examined. The film compatibility and mechanical properties of the grafting copolymer were then evaluated. The results showed that in the vacuum reaction environment, feed weight ratio of meso-lactide and cellulose acetate was 4∶1, catalyst content was 5%, reaction temperature was 140 ℃, reaction time was 30 min, and grafting rate of the product was higher. With the increase of PLA grafting rate, PLA-g-CDA was filmed more easily, and the compatibility as well as the mechanical properties was improved.

Abstract:DHHC-type zinc finger proteins are involved in the palmitoylated modification of intracellular proteins and play important roles in the growth and development of cells and individuals. OsDHHC 13 is a typical DHHC-type zinc finger gene. Bioinformatics analysis showed that the OsDHHC 13 promoter region contains some stress and light response elements, and its encoded protein is a typical membrane protein with four transmembrane domains. When the OsDHHC 13 overexpressing lines were suffered from oxidative stress with H2O2, the roots of overexpressing seedlings were significantly longer than those of wild-type, indicating that OsDHHC 13 can remove the inhibition of root growth by H2O2 and improve the ability of resistance to oxidative stress. Subsequently, analysis of H2O2 contents found that the H2O2 contents in the roots of overexpressing seedlings were markedly lower than that in wild type. qRT-PCR analysis further revealed that the transcriptional levels of enzyme genes related to H2O2 elimination increased significantly, suggesting that OsDHHC 13 can promote the expression of enzyme genes related to H2O2 elimination and regulate the homeostasis of endogenous H2O2 in plants. In a whole, present study preliminarily proved that the zinc finger protein gene OsDHHC 13 positively regulates the ability of resistance to oxidative stress.

Abstract:The Laminated Habitat System (LHS) composed of indigenous species was designed and embedded into a Small Experimental Landscape Pond (SELP). The variation of water quality, eco-habitat and the sink of grey water footprint (WFgrey sink) for the SELP at high spatiotemporal resolution were measured statically outdoor for 20 days. The results showed that the removal efficiencies of TP, TN, NH4+-N, and NO3--N reached 81.01%, 77.1%, 88.82% and 84.12%, respectively, while the removal efficiency of CODCr reached 67.51%, and the concentration of Chl.a decreased to 0.98 μg·L-1. The turbidity reduced to about 10% of its original level, while 22.9% for the sink of grey water footprint. The LHS acted excellently in improving water quality and rehabilitating the eco-habitat, and promoted the eco-succession of SELP from algal-dominated to macrophyte-dominated. Moreover, this study provided a new idea for Landscape Pond ecology maintenance in the light of Grey Water Footprint theory.

Abstract:Phenazine-1-carboxamide is a new pesticide. This paper evaluates the residue of phenazine-1-carboxamide in tomato and three kinds of soils. New methods for determining phenazine-1-carboxamide residue in these matrices were developed by high performance liquid chromatography detection. Phenazine-1-carboxamides from soil with ammonia water + ethanol + dichloromethane = 1+2+3(v/v) and from tomato with acetonitrile were exacted, followed by chromatography columns (basic aluminum) cleanup. The mean recoveries of phenazine-1-carboxamide in soil and tomato were 80.2% to 95.7% and 80.1% to 85.6% respectively, while the relative standard deviations were 2.14% to 4.17% and 4.12% to 5.17%, respectively. The minimum detectable quantity of phenazine-1-carboxamide was 0.2 ng, and the limit of detection was 0.01 mg/kg. In a whole, this method is simple and reliable, and has weak matrix effects, which satisfies the requirement of pesticide residue analysis. It is applicable to determine the phenazine-1-carboxamide residues in soil and tomato.

Abstract:In order to reduce the harm of the nicotine to human body during the suction, the distribution of nicotine interception and flue gas temperature in the cellulose acetate cigarette filter under ISO suction mode was simulated via the standard k-ε turbulence model, SIMPLE algorithm and porous medium model. The results showed that the total enthalpy of air decreased gradually with the time, and the nicotine spread quickly and decreased gradually along the axial direction, because nicotine temperature gradually decreased and nicotine slowly moved down when spreading to the smoking end. Moreover, the nicotine also distributed discretely, which reduced the nicotine intercept efficiency because of the fierce Brownian motion under thermophoretic force along the radial direction. Meanwhile, it is found that the simulation intercept efficiency of cellulose acetate cigarette filter was 30.59%, which was close to the experimental efficiency under the same conditions, and the results can provide theoretical basis for the optimal design of the filter.

Abstract:Modified clinoptilolite saturated with ammonia nitrogen was regenerated by microwave radiation alone and microwave-assisted regeneration solution, respectively. The study showed that the poor regeneration effect was obtained by microwave alone. The adsorption removal efficiency of ammonia onto spent zeolite after regeneration restored to 32.31% under the conditions of the power of 462 W and microwave radiation of 12 min， and the regeneration rate was only 44.88 %. The regeneration effect of the saturated zeolite was highly enhanced by adding mixed solution of NaCl and NaOH. The saturated zeolite achieved the maximum removal rate of about 71.92%, and the regeneration rate was close to 100%, when it was treated in NaCl and NaOH mixed solution concentration of 0.01 mol/L, the ratio of solid to liquid as 1∶50, the power of 700 W, and the microwave radiation of 4 min. For all the zeolites before and after modification, adsorption and regeneration were fully characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS) technique. The results demonstrated that zeolites mainly exhibited cation exchange in the process of modification, adsorption and regeneration. Microwave radiation accelerated the exchange process and deepened the ion exchange equilibrium degree between NH4+ and Na+, which contributes to the NH4+ desorption from zeolite framework fast and completely.

Abstract:Seriousness of the problems caused by sediment deposits in urban sewer pipe has been widely recognized. Using circulating water tank, scouring tests on the sewer sediment with biological activities were carried out, and the influence of biological activities on erosion characteristics of real in-sewer sediment with different volatile solid (VS) contents under open channel flow by controlling the conditions of dissolved oxygen concentrations and incubation time was also investigated. The results indicate that the biological activities exhibited both positive and negative influences on the erosion law of sewer sediment. It improved the anti-erosion capability by enhancing the binding strength between particles, and the erosion resistance was weakened due to the increase of the porosity of the internal structure of the sediment. Meanwhile, the weak biological activities in the sediment with lower organic content can strengthen the erosion resistance with the incubation time. On the contrary, strong biological activities of sediment with high VS content leaded to the weakening of the erosion resistance. The effect of biological activities on erosion characteristic was also related to the shear force of the flow for the sediment with appropriate VS content.