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A discrete element method model was established to simulate 316L stainless steel powder spreading process in selective laser melting. The effects of recoating blade speed, assigned gap width and substrate surface morphology on the powder spreading quality was studied. The results showed that lower recoating speed and larger gap width benefited the quality of powder layer. When the angle between the moving direction of recoater and laser scanning direction was greater than 45 °, the density level of the powder layer on the SLM processing surface was higher than that of the flat substrate and more uniform. The quality of the powder layer on the milled surface varied with position obviously, and the maximum density was between the other two types of surfaces, while uniformity of the powder layer was worse than the other two surfaces. This study shows that the quality of powder layer can be controlled by adjusting the setting parameters of the recoater and the surface morphology of the substrate.

International audience; Herein, a model study of the photoinitiated thiol–ene reaction was carried out on unsaturated fatty methyl esters at room temperature and without photoinitiator. Reaction kinetics were monitored by FTIR spectroscopy and reaction products were identified by high resolution mass spectrometry coupled to ion mobility spectrometry. This set of analytical tools enabled us to highlight the concomitance of fatty double bond oxidation and thiol–ene addition when such a formulation was exposed to UV radiation. Indeed, thiol–ene adducts were identified on fatty moieties oxidized or not, without prevalence of one reaction over the other: photoinitiated thiol–ene addition could occur on preoxidized products, and photooxidation could occur on thiol–ene adducts. However, the presence of oxidized fatty products such as peroxides and zwitterionic species was proved to be favourable to the photocrosslinking of fatty coatings by thiol–ene addition.

In the quest for green and friendly processes in polymer chemistry, we report herein a new process for bio-based coatings as an attractive alternative to the common drying of oils. This process involves the photoinitiated thiol-ene chemistry under air for the preparation of linseed oil-based biocoatings. Several parameters were investigated to determine the optimal formulation composition and irradiation conditions. Native or stand linseed oil triglycerides were then crosslinked in the presence of 0.5 equivalent of various thiols (SH/ene) under 20 min UV exposure, without photoinitiator nor solvent. 10–20 μm thick coatings constituted of about 80 wt% of linseed oil were obtained. They exhibited at least equal physico-chemical properties compared to coatings dried by simple oxidation. It was found that oxidation of fatty moieties occurred during and after irradiation and has a beneficial effect on the properties of the final coatings.

CCD camera calibration technique is an important part of image processing. The calibration accuracy of CCD camera parameters determines the precision of the image processing system. With the development of industry, the demand for image processing precision is increasing, so the precision and robustness of CCD camera calibration technique are required to be higher. In order to further improving camera calibration accuracy and simplifying calibration process, in this paper, we proposed a new method of camera calibration on the basis of the traditional camera calibration technique. Different from the traditional calibration method, this new calibration technique uses a “black box system” to build a link between the ideal image points and actual ones instead of setting up linear CCD camera imaging model (i.e. pinhole imaging model) and nonlinear imaging model about camera distortion. The actual pixel coordinates of the camera image are the input values, and the reprojection points obtained by the world coordinates are the output values. In order to verify the validity of this method, we carry out experiments based on the improved calibration method of zhang zhengyou. 1 And finally we verified the feasibility of this method by comparing the experimental results respectively obtained though carrying out the calibration method this paper proposed and the traditional calibration method by camera calibration toolbox.

Under the scenarios of climate change, balancing the land and water resources is one of the key problems needed to be solved in land development. To reveal the water dynamics of the cultivated land in Naoli River Basin, we simulated the future scenarios by using the future land use simulation model based on Landsat Satellite images, the DEM data and the meteorological data. Results showed that the growth rate of cultivated land gradually decreased. It showed different changing characteristics in different time periods, which led to different balancing effect between land and water resources. In 1990, the water dynamics of the cultivated land resources was in good state, At the same time, the adjustment of crops structure caused the paddy fields increased dramatically. During 2002 to 2014, the cultivated land that in moderate and serious moisture shortage state increased slightly, the water deficit was deteriorating to a certain degree, and maintained sound development of water profit and loss situation gradually. By comparing the simulation accuracy with different spatial resolutions and time scales, we selected 200 m as the spatial resolution of the simulation, and simulated the land use status in 2038. The simulation results showed that the cultivated land's water profit and loss degree in the river basin showed significant polarization characteristic, in that the water profit and loss degree of the cultivated land would be further intensified, the area with the higher grades of moisture profit and loss degree would distribute more centralized, and partially high evaluated grades for the moisture shortage would expand. It is needed to develop the cultivated land irrigation schemes and adjust the cultivated land in Naoli River Basin to balance soil and water resources.气候变化背景下,如何耦合水土资源是当前土地资源利用亟待解决的关键问题之一.为揭示挠力河流域耕地水土资源平衡态势,本文以Landsat影像、数字高程模型(DEM)数据和气象台站数据为基本信息源,结合遥感和GIS技术,运用未来土地利用模拟模型定量模拟RCPs气候情景下耕地的水分盈亏状况.结果表明: 挠力河流域耕地内部结构差异性变化导致水土资源呈现阶段性的平衡特征,1990年耕地水分盈亏状况良好,旱改水农业结构调整导致当地水田迅速扩张,2002年中度和重度缺水区大量增加,水分亏缺态势急剧恶化,至2014年耕地整体水分亏缺状况趋于缓和;通过对比不同空间分辨率及时间尺度下的模拟精度,确定最优模拟空间分辨率为200 m,最优模拟时间点为2038年;模拟结果显示,未来挠力河流域耕地整体呈现出明显的水分盈亏极化特征,即正常缺水、重度缺水和严重缺水区面积将进一步扩大,轻度缺水和中度缺水区呈现收缩态势,高水分盈亏程度指数区分布更加集中,局部高水分亏缺区面积进一步扩大.未来需针对该地区采取针对性的农田水分灌溉措施及耕地调整,以实现水土资源平衡利用.

We revisit the issue of constructing the first-order periodic solution that incorporates the J(22) tesseral harmonic and developing a new semi-analytical solution that may apply to any orbital eccentricity in [0,1). In our work, the solution is expressed in a finite compact form composed of several definite integrals with varying integration intervals constrained in [0, pi], in which the traditional Hansen coefficients are no longer involved. Numerical experiments are also given and compared with the traditional series expansion method, and the results show that the derived solution is capable of dealing with highly eccentric orbits. Therefore, the solution given can provide a new technique to analyze the perturbation characteristics arising from the J(22) harmonic.

In order to study the residual stress distribution in the titanium alloy laser rapid forming parts, the incremental-step hole drilling method is improved. Choose a calibration sample which has the same material as the test sample to conduct internal residual stress measurement by incremental-step hole drilling method. Conduct stress-release heat treatment (insulation 4 hours in 750 centigrade, furnace cooling) to the calibration sample before the measurement to uniform the internal stress. Calculate calibration compensation coefficient according to the calibration sample stress measurement result, and use the compensation coefficient to compensate the stress measurement result of the laser rapid forming sample. This method improves the reliability of internal residual stress measurement by incremental-step hole drilling method. Then use this method to measure the stress of laser rapid forming sample. The result shows that both the residual stress in the X direction and the Y direction is larger when the depth ranges from 1 mm to 3 mm. When the depth is greater than 3 mm, the residual stress decreases gradually with the hole depth increasing. The maximum value in the X direction is 147.13 MPa, and the maximum value in the Y direction is 236.32 MPa.

The Phase Field model of solidification processes was carried out coupled with temperature field model. The influence of interface atomic time on dendrite growth morphology in undercooled melt was simulated with pure nickel. The experimental results show that when the interface atomic motion time parameter is minor, the liquid-solid interfaces were unstable, disturbance can be amplified easily so the complicated side branches will grow, and the disturbance speed up the dendrite growth. With the increase of , the liquid-solid interfaces become more stable and finally the smooth dendrite morphology can be obtained.

Relative dynamics between the chief satellite and the deputy ones in formation flying is crucial to maintaining the formation. A good choice of the formation usually requires a lower control frequency or less control energy. For formation flying missions in highly elliptic orbits, the well-known C-W equation is not accurate enough. Instead, Lawden's equation is often used. First, the solution to Lawden's equation with a very simple form is deduced. Then the J2 perturbation is added. It is found that Lawden's solution is not necessarily valid when the J2 perturbation is considered. Completely discarding Lawden's solution and borrowing the idea of mean orbit elements, two rules to initialize the formation are proposed. The deviation speed is greatly reduced. Different from previous studies on the J2 perturbation, except for the relatively simple expression for the semi-major axis, the tedious formulae of the long period terms and the short period terms of other orbital elements are not used. In addition, the deviation speed is further reduced by compensation of the nonlinear effects. Finally, a loose control strategy of the formation is proposed. To test the robustness of this strategy, a third body perturbation is added in numerical simulations.

What is the central question of this study? High titres of autoantibodies against the second extracellular loop of the β

Hyperlipidemia is a major cause of atherosclerotic cardiovascular disease. Poria cocos (PC) is a medicinal product widely used in Asia. This study was undertaken to define the alterations of lipid metabolites in rats fed a high-fat diet to induce hyperlipidemia and to explore efficacy and mechanism of action of PC in the treatment of diet-induced hyperlipidemia. Plasma samples were then analyzed using UPLC-HDMS. The untreated rats fed a high-fat diet exhibited significant elevation of plasma triglyceride and total and low-density lipoprotein (LDL) cholesterol concentrations. This was associated with marked changes in plasma concentrations of seven fatty acids (palmitic acid, hexadecenoic acid, hexanoylcarnitine, tetracosahexaenoic acid, cervonoyl ethanolamide, 3-hydroxytetradecanoic acid, and 5,6-DHET) and five sterols [cholesterol ester (18:2), cholesterol, hydroxytestosterone, 19-hydroxydeoxycorticosterone, and cholic acid]. These changes represented disorders of biosynthesis and metabolism of the primary bile acids, steroids, and fatty acids and mitochondrial fatty acid elongation pathways in diet-induced hyperlipidemia. Treatment with PC resulted in significant improvements of hyperlipidemia and the associated abnormalities of the lipid metabolites.

Herein, we report the use of the photoinitiated thiol–epoxy chemistry for the preparation of a new biosourced self-healing coating. Epoxidized cottonseed oil is used as the main reagent (>80 wt%) and photocrosslinked in the presence of 0.25 equivalents of 7-mercapto-4-methyl coumarin, used as a photodimerizable and healable reactant. The reaction is initiated with 2 wt% of a photobase generator (PBG). The stability of the thiol–epoxy mixture under storage and the oxygen-promoted photoinitiating system are some of the advantages illustrated in this study. The physicochemical properties of the resulting coatings as well as the photoreversibility of the coumarin derivative once grafted on the vegetable oil are studied. The photoinitiation step is demonstrated to be efficient for the grafting of the healing reagent as well as for epoxy homopolymerization.

An F1 mapping population containing 94 individuals, derived from the cross between Fengliduo as female and Dawuyuan as male parent, were used in this experiment. Trunk girth, whose segregation situations were investigated on the mapping population in four successive years, showed a continuous distribution. QTL interval mapping for trunk girth was conducted utilizing the Longan molecular genetic map. A total of 26 QTLs which fell into 13 parental linkage groups were detected, but they were not evenly distributed. There existed clumped QTLs in linkage group FLD2, FLD4, FLD5, DWY8 and DWY9. Trunk QTLs could be detected for data from successive years in close positions for 5 genome regions.

The microscopic phase field approach was applied for modeling the early precipitation process of Ni75AlxV25-xalloy. Without any a prior assumption, this model can be used to simulate the temporal evolution of arbitrary morphologies and microstructures on atomic scale. Through the simulated atomic pictures, calculated order parameters and volume fraction of the θ (Ni3V) and γ′ (Ni3Al) ordered phases, Ni75AlxV25-xalloys with Al composition of 0.05, 0.053 and 0.055 (atom fraction) were studied. Results show: For these alloys, θ and γ′ precipitated at the same time. With the increase of Al content, the amount of γ′ phase is increasing and that of θ phase is decreasing; the precipitation characteristic of γ′ phase transforms from Non-Classical Nucleation and Growth (NCNG) to Congruent Ordering + Spinodal Decomposition (CO+SD) gradually, otherwise, the precipitation characteristic of θ phase transforms from Congruent Ordering + Spinodal Decomposition (CO+SD) to Non-Classical Nucleation and Growth (NCNG) mechanism gradually. Both θ and γ′ has undergone the transition process of mixture precipitation mechanism with the characteristic of both NCNG and CO+SD mechanism. No incontinuous transition of precipitation mechanism has been found.

In this paper, taking the characteristics of NGI (Next Generation Internet) into account, and base on its network model and mathematical model, a probability theory based intelligent QoS multicast routing algorithm is presented. Under inaccurate information of QoS parameters, using fast searching ability of DE (Differential Evolution), the proposed algorithm tries to find a multicast routing tree with the maximum probability of meeting with QoS requirement under the given cost. Simulation results have shown that the proposed algorithm is both feasible and effective.

The titanium alloy direct laser fabrication process, the collapse of a side issue has interference and preventing the forming quality and forming precision. This thesis mainly contain with of temperature field analysis and actual observation, by changing the scanning mode to solve this issue. The new scanning mode, dam-type, has a good property and proves that the direct laser fabrication parameters can be complete without change through the whole forming process, and puts the process of control simply.

Taking transfer orbits of a collinear libration point probe, a lunar probe and an interplanetary probe as examples, some applications of stable and unstable invariant manifolds of the restricted three-body problem are discussed. Research shows that transfer energy is not necessarily conserved when invariant manifolds are used. For the cases in which the transfer energy is conserved, the cost is a much longer transfer time.

Objective To investigate the protective effects of acupuncture pretreatment on ischemic myocardium, the protective mechanism of acupuncture pretreatment on ischemic myocardium was explored by observing the cardiac muscle cell apoptosis and the expression of HSP70 mRNA of ischemia-reperfusion injury rats treated with acupuncture pretreatment.

The anisotropy problem of 3D phase-field model was studied, and various degrees of anisotropy were simulated by numerical calculation method. The results show that with the change of interface anisotropy coefficients, from smooth transition to the appearance of angle, equilibrium crystals shape morphology has a critical value, and 3D critical value is 0.3. The growth of dendrites is stable and the interface is smooth when it is less than critical value; the interface is unstable, rolling edge appears and the growth is discontinuous when it is more than critical value. With the increase of anisotropy coefficients, the dendrites grow faster under the same condition.

The adsorption behaviors of polar carbamate pesticide methomyl [(CH 3 S)(CH 3 )C N O (C O) NH CH 3 or S -methyl- N -(methylcarbamoyloxy) thioacetimidate] on marine sediments treated by different methods were investigated. Ten hours were required for adsorption equilibrium of methomyl on sediments. The adsorption isotherms of methomyl on all sediments could be described by Freundlich equation very well. Adsorption of methomyl was completed mainly via the surface H-bond forces between function groups of organic constituents and methomyl molecules. In addition, microporosity action of clays and the van der Waals forces between clays and methomyl molecules might also play important roles in the adsorption of methomyl on sediments. Some external factors which could affect adsorption behaviors of methomyl were also investigated in the present study. Our results showed that the adsorption capacity of methomyl on the sediment decreased with increasing temperature and pH value. Moreover, the adsorption capacity of methomyl on the sediment appeared to be lower in natural seawater than in diluted seawater.

The microwave-assisted conventional HNO3–HF–H2O2–H3BO3 digestion system has been explored for direct ICP-MS analysis of total metals in silicon-containing solid samples. In closed Teflon PFA vessels under microwave heating with temperature/pressure regulation, a 0.25 g portion of sample containing ⩽ 33% silicon was digested in 1.5 ml of HF (48%), 5 ml of concentrated HNO3 and 2 ml of H2O2(30%), followed by a second digestion stage with 12 ml of 5% m/v boric acid. The amount of HF used was approximately twice the stoichiometric requirement for 33% silicon contained in the samples, assuming all silicon exists as silica. The amount of boric acid used was the stoichiometric requirement for the HF added. With a sample dilution factor of 2000 (v/m), the end solution contained ⩽ 0.17% total dissolved solids for ICP-MS analysis. The ICP-MS system was calibrated by the method of external standards prepared in reagent blank solutions with in as the internal standard. The sensitivity of the In signal in a 5–8 h operation was only decreased by 5–10%. Background interferences from the digestion reagents were studied and corrected. The method developed is simple and rugged and suitable for routine analysis of at least 25 elements: Al, Ag, As, Ba, Bi, Cd, Co, Cr, Cu, Fe, Li, Mg, Mn, Mo, Ni, Pb, Sb, Sn, Sr, Th, Ti, Tl, U, V and Zn. The recoveries for most of these elements in standard reference materials including coal fly ash, urban particulate matter, sediment and soil were within 90–110%, and the relative standard deviations were within 5%. The method cannot determine B and is not suitable for Hg determination. The detection limits for Be and Se determination are not adequate.

It is very difficult for an explorer to orbit a low-mass and irregularly shaped small body in the solar system. In this case, formation flying with the small body is a workable solution. This paper discusses two strategies of formation flying based on two different dynamic models. The orbit resulted from the C–W equation and the halo orbit around libration point L1 in the Circular Restricted Three-body Problem (CRTBP) are considered as nominal orbit respectively. Numerical simulation indicates the effect of the magnitude of μ on the stability and other features of the halo orbits, where μ is a parameter weighing the gravity of the small body. The result shows that the CRTBP is more fuel-saving and therefore a more appropriate dynamic model for solving the formation flying problem. This paper also works out a dynamic model involving solar radiation pressure. Simulation result shows that, in this condition, the C–W equation has no significant advantage.

The distribution of ATPase in pollen of Allium cepa L. was studied using Pb3 precipitation technique during pollen development. Only some ATPase precipitates were located in the nucleus of microspore mother cells (MMC) and a few in its cytoplasm. After meiosis of MMC,many ATPase precipitates appeared in the exine of pollen wall of microspore even it was in tetrad, suggesting that ATPase from tapetum is necessary during pollen wall construction. The intine of pollen wall of microspore was synthesized at its late stage and consisted of cellular material which was from microspore. There were also many ATPase precipitates in intine,and the ATPase came from microspore. Then ATPase precipitates in vegetative cell increased and that in generative cell decreased during the development of 2-cellular pollen,suggesting the differentiation of vigor between both cells. The physiological functions of ATPase in developing pollen of Allium cepa L. were analyzed.

CpG islands (CGIs) in human genomic DNA are GC-rich fragments whose aberrant methylation is associated with human disease development. In the current study, methylation-sensitive mirror orientation selection (MS-MOS) was developed to efficiently isolate and enrich unmethylated CGIs from human genomic DNA. The unmethylated CGIs prepared by the MS-MOS procedure subsequently were used to construct a CGI library. Then the sequence characteristics of cloned inserts of the library were analyzed by bioinformatics tools, and the methylation status of CGI clones was analyzed by HpaII PCR. The results showed that the MS-MOS method could be used to isolate up to 0.001% of differentially existed unmethylated DNA fragments in two complex genomic DNA. In the CGI library, 34.1% of clones had insert sequences satisfying the minimal criteria for CGIs. Excluding duplicates, 22.0% of the 80,000 clones were unique CGI clones, representing 60% of all the predicted CGIs (about 29,000) in human genomic DNA, and most or all of the CGI clones were unmethylated in human normal cell DNA based on the HpaII PCR analysis results of randomly selected CGI clones. In conclusion, MS-MOS was an efficient way to isolate and enrich human genomic CGIs. The method has powerful potential application in the comprehensive identification of aberrantly methylated CGIs associated with human tumorigenesis to improve understanding of the epigenetic mechanisms involved.

To investigate the effects of substance P on cultured rat osteoclasts.Neurokinin-1 (NK1) receptor expression in osteoclasts was examined by immunohitochemical method, and changes of bone resorption activity caused by substance P and NK1 receptor antagonists were detected by pit formation assay.Immunoreactivity for NK1 receptor was distributed in the cytoplasm of osteoclasts. The average of pit formation areas significantly increased with addition of substance P (10(-7)-10(-4) mol/L) (P0.05), but the number of pitformations did not change (P0.05). NK1 receptor antagonists inhibited the enhancement of the bone resorption by substance P addition.The findings suggested that substance P may stimulate osteoclasts and result in bone resorption by the mediation of NK1 receptor.