Abstract:The three point bending fatigue behaviors of WC Co cemented carbides with different binder phase content and composition under cyclic loading at two different stress ratios (R=0.1 and R=0.5) were investigated. The characterization of the fracture surfaces was carried out by using a scanning electron microscope (SEM), and the fatigue mechanism was also studied. The results show that the macroscopic fracture morphology exhibited brittle fracture and toughness fracture. With the increase of Co content, the fatigue sensitivity decreased firstly and then increased. Cemented carbides with complex binder phase (Co + Ni + Cr) exhibited lower fatigue sensitivity than that of pure Co cemented carbides. The fracture mechanism transformed from brittle to ductile at the stress ratio changing from 0.1 to 0.5. With the increase of the stress ratio, the fatigue sensitivity was changed.

Abstract:7A85 aluminum alloy，possessing the characteristics of low density，high strength，excellent hot working property，fine weldability，good corrosion resistance and high toughness，has been widely used in aerospace and mechanical structural parts.High temperature rheological behavior and microstructure evolution of as extruded 7A85 aluminum alloy were investigated by optical microscope（OM），transmission electron microscope（TEM）and the unidirectional isothermal compression tests conducted at different temperatures（300，350，400 and 450℃）with different strain rates of 0.01，0.1，1 and 10 s-1.It is concluded that the deformation temperature and strain rate have an important effect on the microstructure of the as extruded 7A85 aluminum alloy after hot compression.With the increase of deformation temperature and the decrease of strain rate（decreasing of lnZ），the subgrains and the recrystallization grains grow，the dislocation density and the quantity of precipitates decrease，and the softening mechanism transforms from dynamic recovery to dynamic recrystallization.Plenty of precipitates of as extruded 7A85 aluminum alloy after hot compression，dispersing in the matrix or along the grain boundaries，inhibit the occurrence of dynamic recrystallization.

Abstract:The effect of pre deformation and ageing on mechanical properties and microstructure of 7N01 alloy was investigated by means of process optimization, mechanical property measurement and microstructure characterization. The results show that, compared with single deformation and aging treatment, a suitable combination of pre deformation and thermal aging can significantly improve the mechanical properties of the material. In this study, sample processed with a 10% pre deformation and followed by 120 ℃ aging treatment had the best mechanical property with 430 MPa yield stress and 470 MPa tensile strength, respectively. Meanwhile, the elongation still maintained as 14%. The dislocation introduced during pre deformation played a key role on the types, size and distribution of precipitates in the subsequent aging treatment, which affected the final mechanical properties of the alloys.

Abstract:The method to use high Si composition SiC particle reinforced Al Si alloy to make automotive engine piston by upsetting extrusion was proposed.The forging process mold of piston was designed.The influence on microstructure and mechanical properties of composition Particle Reinforced Al Si alloy by the technological parameters including forging speed，initial forging temperature，holding time of the billet on formability was studied．The results show that gradient distributed SiC particle reinforced Al Si alloy can be made by this method.The SiC particle distributing inside from piston skirt to ring groove zone was 3.7% to 13.6%.The formability of the Al 20%Si/SiCp alloy by spray forming was better with the initial forging temperature at 465 ℃，the forging rate was 0.05 s-1，and the holding time of the billet was 2 h.After solution and aging heat treatment on the piston，the tensile strength is reaching 382 MPa and the elongation of 6.0%.

Abstract:The mechanical properties, microstructure, and crack initiation and propagation of U71Mn steel rail after service were studied by the techniques of microsclerometer, optical microscope, scanning electron microscope (SEM), and energy disperse spectroscopy. The results indicate that the hardening degree on the gauge corner of the rail is the most serious, and the plastic deformation is very serious in this section. Thus, the crack may initiate on the gauge corner, and the crack initiation is influenced by the shear stress, surface friction coefficient and inclusions. Meanwhile, the microstructure on the surface will deform again and again under the cyclic stress, and the breakdown of the grains will harden the materials and decrease the toughness and ductility. Moreover, there are many lath shape MnS inclusions in the rail, which all promote the initiation of the crack. The crack in the rail propagates along the surface plastic deformation, and the path of crack growth is transgranular. There is much iron oxide in the gap of the crack, which can also promote the propagation of the crack.

Abstract:In order to analyze the microstructure evolution and grain growth processes of coarse grain heat affected zone(CGHAZ), fine grained heat affected zone (FGHAZ), and intercritical heat affected zone (ICHAZ), 12 mm SS400 medium plate was welded under different heat input. The varying rules of the HAZ width, microstructure and microhardness with the variation of heat input in welding HAZ and all sub areas were studied using the finite element method in combination with microscopic tests. A relationship between the heat input and HAZ width which follows the Boltzmann distribution was also presented. The result shows that when the steel was welded with heat input of 9.6~22 kJ/cm, the effect of the heat input on the width of HAZ and all sub areas was small; the width of HAZ increased when the heat input was higher than 22 kJ/cm, especially leading to the substantial increase of width in FGHAZ. Moreover, when the heat input increased, the hardness peak of the joint became higher in CGHAZ which was caused by a restraint of the lamellar bainite transformation and the widmanstatten formation, while the softened zone expanded gradually. Preheating can restrain the growth of the HAZ width for the welding with high heat input.

Abstract:A sintered hypoeutectic high chromium cast iron （SHCCI） was fabricated by a powder metallurgy process with water atomized powders as raw materials. Its microstructure，mechanical properties and impact abrasion resistance were systematically analyzed or/and detected，and compared with an as cast high chromium cast iron （CHCCI） with the same composition. The results showed that the density of SHCCI could be of 7.44 g/cm3 as supersolidus liquid phase sintering was applied. There was only Cr7C3 type carbides in SHCCI，and its matrix with fine grain size was a hybrid of a major part of martensite and austensite. The short rod shape Cr7C3 carbides were homogeneously dispersed along grain or subgrain boundaries. The hardness，bending strength and impact toughness（specimens with dimensions of 5 mm×5 mm×50 mm were used）of the as sintered SHCCI were of HRC58，2 122 MPa and 6.5 J/cm2，respectively. With the dramatical improvement of morphology，size and distribution of carbides as well as more amount of martensite in the matrix，as sintered SHCCI presented evident advantages of impact abrasive resistance under all kinds of impact charges over CHCCI.

Abstract:The influence of high temperature oxidation time on the composition, microstructure, and mechanical and electrical properties of MoSi2 RSiC composites was discussed. The experimental results show that the oxidation of composites mainly formed a dense cristobalite SiO2 film on the external surface. The mechanical properties of the composites increased and then decreased with the increase of oxidation time, and MS 2.62 oxidized for 40 h achieved the maximal flexural strength and elastic modulus of 146.03 MPa and 239.49 GPa, respectively. Meanwhile, the mechanical properties of composites were still greater than those of samples without any oxidation even after 100 h oxidation. With the increase of oxidation time, the volume resistivity of MoSi2 RSiC composites decreased and then reached a flat, while the volume resistivity of MS 2.62 was about 50 mΩ·cm after 100 h oxidation, which was about 42% lower than its original values. Additionally, the calculated influence factor I indicated that this variety might be caused by the healing of micro crack at the interface between RSiC and MoSi2 induced by the plastic deformation of MoSi2, resulting in the decrease of the volume resistivity of composites.

Abstract:Microwave assisted ball milling was employed to reduce Cr (VI) in wastewater, and single factor method was used to observe the change of the iron ball quality, the amount of reduced iron powder and the effect of pH on the reduction of Cr (VI). These experimental results show that the greater the ball material ratio and the amount of reduced iron powder, the smaller the pH, the faster the reduction speed of Cr (VI). In the neutral solution, through microwave assisted ball milling, the concentration of Cr (VI) can be reduced from 50 mg/L to 0.473 mg/L in 55 minutes, and the production is detected as FeCr2O4 by XRD with XPS. When the pH is 2, the initial concentration of 300 mg/L Cr (VI) can be reduced to below 0.5 mg/L in 6 minutes. Therefore, the industrial wastewater containing Cr (VI) can be efficiently disposed by microwave assisted ball milling equipment.

Abstract:A non contact laser micrometer was introduced to a conventional single filament tensile testing instrument to directly measure small displacement of stiff fiber samples，allowing strength，modulus and strain of single filaments to be measured simultaneously and accurately.Complicated system corrections were eliminated by using this laser micrometry method.Experimental results obtained from T300 carbon fibers agreed well with the data provided by manufacturer in term of accuracy，a nonlinearity in modulus for the carbon fiber sample was observed during extension，further indicating that laser micrometry method is capable of measuring strain and modulus directly and accurately，especially for high modulus materials.The markers attached to the fiber specimen appeared to be the key to accurate measurements，the effects of the shape,size and material of markers were experimentally studied.It is showed that markers should be opaque with straight parallel sides and perpendicular to the fiber axis.

Abstract:The sintering additives have directly influenced on the phase composition such as crystal phase, glass phase and pore, and then affected the mechanical properties of porcelain material. The additives (ZnO, TiO2, and ZrSiO4) with 2% were added respectively into the billets of porcelain, followed by manufacturing the mud, dehydration, vacuum pressing, extruded reagent strips and sintering simultaneously in industrial kiln with the products. The reagent strips were tested for their bending strengths. Meanwhile, the scanning electron microscopy (SEM) was adopted to observe the microstructure, and X ray diffraction (XRD) was used to determine the phase. The results show that sintering additives can significantly improve the bending strength of the reagent strips, reduce the porosity of the samples, improve the density and reduce the amount of primary mullite dramatically, while secondary mullite developed and intertwined with small amounts of quartz and cristobalite phase.

Abstract:Existing studies have shown that electrical field accelerates the sulfate attack, and thus it can be used to rapidly evaluate the sulfate resistance of cement based materials. However, Na2SO4 was mainly used as the corrosion medium in these studies and there were fewer researches on MgSO4 as attack solution under electrical field. Therefore, in this paper, the mechanism of magnesium sulfate attack under electric field was analyzed by means of corrosion resistance coefficient, X ray diffraction (XRD) and Scanning Electron Microscope (SEM) equipped with Energy Dispersive Spectrometer (EDS). The results showed that sulfate ions migrated into the specimens under the action of electrical field and reacted with portlandite to produce gypsum, which reacted further with the hydration products of C3A to form ettringite. After the hydration products of C3A were consumed, the penetrated sulfate ions continued to react with portlandite. As a result, the main attack product was gypsum, followed by ettringite.

Abstract:Based on SMA 13 asphalt mixture,the pavement performance of a kind of organic warm mixed additive in dry and wet process was evaluated,and compared with that of SBS asphalt mixture. The experimental results show that the warm mixed additive can be used as a modifier to give larger modulus and higher temperature viscosity,keep the stability of visco elasticity structure in 30~65 ℃ranges,and reduce the temperature sensitivity of neat asphalt. In dry method application,after the surface pretreatment of basalt particles,this warm mixed additive can effectively improve the cohesive grade between neat asphalt and aggregate. By using the same production temperature of neat asphalt,the SMA mixture with 03% warm mixed additive production in dry process can meet the requirement of the modified asphalt mixture,get the pavement performance close to that of SBS asphalt mixture,and achieve a warm mixing effect.

Abstract:The influence of catalytic polymerization temperature and time on structure and properties of the synthesized naphthalene pitch prepared by using naphthalene as raw material and HF/BF3 as catalyst was studied.The molecular structure of naphthalene pitch was investigated by elemental analysis (EA),infrared spectroscopy (FT〖CD*2〗IR),nuclear magnetic resonance spectroscopy (1H〖CD*2〗NMR) and mass spectrometry (MS) analyses.The results show that the softening point(SP.),coking value,toluene insoluble(TI) and aliphatic hydrogen especially Hβ content of naphthalene pitch increase but the aromatic hydrogen content reduces with the increases of catalytic polymerization temperature and the holding time. More content of naphthenic structures and lower methyl content were found in naphthalene pitch synthesized in higer catalytic polymerization temperature.

Abstract:Surface properties of tissue engineering scaffold play important roles in cell adhesion and other biological processes such as cell proliferation,differentiation. In this study,the surface modification of Poly (3 hydroxybutyrate co 3 hydroxyvalerate) (PHBV) was performed in order to improve the biological activity of material surface. PHBV nanofibrous scaffold was firstly made by electrostatic spinning method,introducing free amino groups in the PHBV surface through 1,6 hexanediamine,which provided reaction sites for the further immobilization of hyaluronic acid (HA) macromolecules. The morphology observed by SEM showed that PHBV nanofibrous scaffolds prepared by electrostatic spinning method have smooth surfaces without obvious beads defects and their fiber diameters uniformly distribute. FTIR analysis proved that 1,6 hexanediamine and hyaluronic acid modified PHBV fibrous scaffolds were successfully achieved. The ninhydrin determination results showed that the surface amine group density,which increased with the extending of aminolysis time,reached its maximum at 50 minutes. Furthermore,there is no significant difference on the morphology of the scaffolds before and after modification by statistic comparison. The water contact angle significantly decreased after the immobilization of hyaluronic acid,indicating that the hydrophilicity was obviously improved after surface modification with the hydrophilic natural biological macromolecules. The Alamar Blue assay manifested that hyaluronic acid modified PHBV nanofibrous scaffolds could significantly promote the chondrocytes proliferation in vitro. Therefore,the hyaluronic acid modified PHBV nanofibrous scaffolds are potential for application in cartilage tissue engineering.

Abstract:Amphiphilic triblock copolymer mPEG b P1 b mPEG,with disulfide bond in the main chain of the hydrophobic block,was prepared from cystamine dihydrochloride,allyl chloroformate,1,6 hexanedithiol and monomethoxy poly (ethylene glycol) with a thiol end group through thiolene click chemistry method. Self assembly of the obtained mPEG b P1 b mPEG was further investigated. The results showed that the critical micelle concentration of the amphiphilic block polymer was 0.032 mg/mL,and the average diameter of the micelle was about 61.3 nm. The loaded model drug Nile Red could be released from the micelles in the presence of DTT,indicating the reduction responsiveness of the obtained amphiphilic copolymer. Therefore,these findings suggested the potentials of the amphiphilic copolymers as smart intracellular drug delivery systems.

Abstract:A series of UV curable polyurethanes that were compounded based on polydiethylene glycol 2000 as soft segments,different glycol chain extenders and isophorone diisocyanate (IPDI) as hard segments,and 2 Hydroxyethyl acrylate (HEA) as blocking agent were synthesized by prepolymer method. The relative activities of different glycol chain extenders as chain extenders were analyzed: the structure of UV curable polyurethane was characterized by infrared spectral,and the influences of different glycol chain extenders on the mechanical performance,heat resistance performance and usability of cured film were studied. The results show that under 80 ℃,the reaction speed of ethylene glycol and phenyl isocyanate(PI) is the fastest,the speed of 1,2 propylene diatomic alcohol and PI is the slowest,and 1,4 cyclohexane dimethanol(CHDM) as chain extender of PU has the best mechanical properties and heat resistance.

Abstract:The flotation of oxidized zinc ore was investigated by using α nitroso β naphthol as activator and octadecylamine as collector.The results indicated that the dosage of the activator and collector，the type and content of dispersant were the main affecting factors on the Zn grade and recovery from zinc oxide ore.The artificial mixture flotation tests indicated that the grade of zinc was up to 3826% from the initial grade of 2230%，and the optimal flotation recovery was found at 8790% using calcium lignosulphonate as dispersant after activation with α nitroso β naphthol at pH 95It implied that α nitroso β naphthol was an effective activator for the flotation of oxidized zinc ore.The results of IR spectrum suggested that a six membered ring coordinated from O to Zn was formed between α nitroso β naphthol and Zn2+ on the mineral surface，resulting in the enhancement of the hydrophobicity of the mineral surface.

Abstract:An endophytic bacteria strain CcSh 1 that produced obvious fragrance was successfully isolated from the sheath of Cymbopogon citrates (DC.)Stapf. CcSh 1 strain was identified as Pantoea ananatis by the morphological observation,physiological and biochemical characterization and 16S rRNA sequence analysis. Headspace gas chromatography mass spectrometry detection showed that the volatile organic components of CcSh 1 were terpenoid and mainly contained citral,which were similar to those of C. citrates and their essential oil. The factors involved in the flavor productivity and the growth status of CcSh 1 were also investigated,and the optimal liquid culture conditions for CsSh 1 were confirmed by taking beef extract as carbon source,and the peptone as nitrogen source,under the temperature of 30℃ and pH 7.0. In addition,it was discovered that the addition of 1% (w/v) abrasive of host plant as substrate can promote the flavor production of CcSh 1,which indicated the interaction between endophyte and its host.

Abstract:To study the mechanism of tobacco nicotine conversion,the expression of nicotine conversion related proteins of high tobacco nicotine conversion was explored by differential proteomics. Two dimensional electrophoresis combining MS spectrometry were used to compare the expression of the proteins between high nicotine conversion tobacco (experimental group) and wild type tobacco (control group). After obtaining the distinguishable and repeatable 2 D pictures,there were 34 different proteins spots between the two tobacco plant leaves.12 different protein spots were then identified by the Matrix Assisted Laser Desorption/ Ionization time of Flight Mass Spectrometry Mass Spectrometry (MALDI TOF TOF MS),including 7 protein spots down regulated in white flower leaves (experimental group),and 5 protein spots up regulated. In addition to comparison analyses with proteomic database,these proteins are involved in carbohydrate,energy metabolism and so on. Most of them are chloroplasts or mitochondria proteins. In a whole,these differential expression proteins were closely related with tobacco nicotine conversion,which can provide another pathway for finding the mechanism of tobacco nicotine conversion.

Abstract:In view of the source of heavy metal pollution produced by the lead zinc tailings,a static leaching simulation test was carried out to study the different environmental influence factors on dissolution of zinc and arsenic in acidified sulfide mine tailings,taking the lead zinc tailings in Qinghai Province and acidithiobacillus ferrooxidans as the research objects. The main reasons and rules of the heavy metals release were analyzed during different periods so as to provide theoretical basis for the heavy metal pollution prevention and control of lead zinc tailings. The research results show that the relationship between Zn cumulative release amount of unit mass and the initial pH value of the solution expressed as pH2.0 > pH3.5 > pH4.5 was a negative correlation. The more the concentration of tailings was,the less the oxygen in contact with minerals was,and the less release of Zn and As. Compared with the leaching system without sodium sulfite,the release rules of heavy metals were obviously different,the added sodium sulfite increased the pH value of liquid and inhibited the release of Zn and As. Meanwhile,it is found that the release of Zn and As can be characterized into two stages. The early stage was given priority to acid solution and oxidation reduction. Adsorption and deposition reduced the release amount at the second stage. The new generated CaSO4 and Brushite covering mineral surface in the last stage also inhibited the continuous release of heavy metals. Release amount of Zn was greater than that of As,and the dissolution order is started from Zn to As,which can be attributed to the galvanic effect and more sensitiveness of Zn to the acid solution.

Abstract:To understand the soil background situation of a typical southern province,468 background points were established. Through sample collection and experimental analysis,the pollution situation of these background points was comprehensively investigated. At first,this study analyzed the inorganic elements and organic pollutants of different soil utilization types in this province,compared the pollutants distribution characteristics of different profiles,and then evaluated the soil environmental quality of background points. Finally,through t test of the“7th Five year Period”background data and the investigation data in this study,it is concluded that environment quality of paddy fields and dry land solid keeps stable and the inorganic pollutant content in forestry solid mostly declines.

Abstract:At home and abroad,many studies of bacterial technology to remove NO and NOxhave been performed. However,the effect and mechanism of fungal were poorly studied. To improve the removal efficiency of NO and NOx,the fungi isolated and identified from the biofilm of denitrifying tower through shaking flasks experiment was studied on its nitrogen removal characteristics to nitrate (NO3 ). Expanding culture was put into the denitrify tower to study its effect on the NO and NOx removal efficiency. The fungal community structure through high throughput sequencing analysis was monitored. The results showed that the strain 3LNB through morphological,nitrogen (NO3 ) removal characteristics research,and ITS sequence analysis was identified as Fusarium solani. For up to 10.01 g/L of NO3 _N,the denitrifying rate of bacteria control group was 5.6% with nitrogen removal efficiency of 0.56 g/L,but the denitrifying rate of strain 3LNB was 15.1% with nitrogen removal efficiency of 1.51 g/L for 10 days,which proved that the strain 3LNB had strong denitrification function. The nitrogen removal rate of NO and NOxwas increased by 5.12% and 5.36% on average,respectively,after the expanding culture 400 mL (4%) of pure strain 3LNB was put into denitrifying tower,which proved that the strain 3LNB culture can improve removal rate of NO and NOxin denitrifying tower. This may be mainly related to the presence of cytochrome P450nor in fungi such as Fusarium solani.

Abstract:Long term ecological and physiological toxicity caused by the residuals of fluoroquinolones (FQs) in the aquatic environment has raised much attention. Ciprofloxacin as a typical FQs was degraded by UV activated persulfate,which was a new advanced oxidation technology. The degradation products were characterized using qualitative and quantitative methods,and the detailed degradation mechanism and pathways of ciprofloxacin by UV/persulfate were proposed by using the analysis results of quantum chemistry and mass spectra. The results revealed that the optima condition for CIP degradation was pH 9.0. After a 30 min reaction,13 intermediates were identified in the solutions,including alcohols,phenols,ketones and amides. The concentrations of several intermediates exhibited an up and down trend. Oxidations mainly occurred at the C F bond and carboxylic acid on quinolone group,as well as piperazine group. The degradation of CIP by UV/PS mainly included four pathways,and a series of defluorination,photolysis,substitution,addition and deamination were observed,leading to the final open ring reaction of target compound.