The first factor affecting dryland winter wheat grain yield under various mulching measures: Spike number

Water is the key factor limiting dryland wheat grain yield.Mulching affects crop yield and yield components by affecting soil moisture.Further research is needed to determine the relationships between yield components and soil moisture with yield,and to identify the most important factor affecting grain yield under various mulching measures.A long-term 9-yearifeld experiment in the Loess Plateau of Northwest China was carried out with three treatments:no mulch (CK),plastic mulch (M_(P)) and straw mulch (M_(S)).Yield factors and soil moisture were measured,and the relationships between them were explored by correlation analysis,structural equation modeling and significance analysis.The results showed that compared with CK,the average grain yields of M_(P) and M_(S) increased by 13.0and 10.6%,respectively.The average annual grain yield of the M_(P) treatment was 134 kg ha^(–1) higher than the M_(S) treatment.There were no significant differences in yield components among the three treatments (P<0.05).Soil water storage of the M_(S) treatment was greater than the M_(P) treatment,although the differences were not statistically signifiant.Soil water storage during the summer fallow period (SWSSF) and soil water storage before sowing (SWSS) of M_(S) were significantly higher than in CK,which increased by 38.5 and 13.6%,respectively.The relationship between M_(P) and CK was not statistically significant for SWSSF,but the SWSS in M_(P) was significantly higher than in CK.In terms of soil water storage after harvest (SWSH) and water consumption in the growth period(ET),there were no signi?cant differences among the three treatments.Based on the three analysis methods,we found that spike number and ET were positively correlated with grain yield.However,the relative importance of spike number to yield was the greatest in the M_(P )and M_(S) treatments,while that of ET was the greatest in CK.Suifcient SWSSF could indirectly increase spike number and ET in the three treatments.Based on these results,mulch can improve yield and soil water storage.The most important factor affecting the grain yield of dryland wheat was spike number under mulching,and ET with CK.These findings may help us to understand the main factors influencing dryland wheat grain yield under mulching conditions compared to CK.

The influence of inter-band rock on rib spalling in longwall panel with large mining height

In order to improve rib stability,failure criteria and instability mode of a thick coal seam with inter-band rock layer are analysed in this study.A three-dimensional mechanical model is established for the rib by considering the rock layer.A safety factor is defined foy the rib,and it is observed that the safety factor exhibits a positive correlation with the thickness and strength of the inter-band rock.A calculation method for determining critical parameters of the rock layer is presented to ensure the rib stability.It is revealed that incomplete propagation of the fracture at the hard rock constitutes a fundamental prerequisite for ensuring the rib stability.The influence of the position of the inter-band rock in the coal seam on failure mechanism of the rib was thoroughly investigated by developing a series of physical models for the rib at the face area.The best position for the inter-band rock in the coal seam is at a height of 1.5 m away from the roof line,which tends to provide a good stability state for the rib.For different inter-band rock positions,two ways of controlling rib by increasing supports stiffness and flexible grouting reinforcement are proposed.

Optimized NPK fertilizer recommendations based on topsoil available nutrient criteria for wheat in drylands of China

The optimized management of crop fertilization is very important for improving crop yield and reducing the consumption of chemical fertilizers.Critical nutrient values can be used for evaluating the nutritional status of a crop,and they reflect the nutrient concentrations above which the plant is sufficiently supplied for achieving the maximum potential yield.Based on on-farm surveys of 504 farmers and 60 field experimental sites in the drylands of China,we proposed a recommended fertilization method to determine nitrogen(N),phosphorus(P),and potassium(K)fertilizer input rates for wheat production,and then validated the method by a field experiment at 66 different sites in northern China.The results showed that wheat grain yield varied from 1.1 to 9.2 t ha^(-1),averaging 4.6 t ha^(-1),and it had a quadratic relationship with the topsoil(0-20 cm)nitrate N and soil available P contents at harvest.However,yield was not correlated with the inputs of N,P,and K fertilizers.Based on the relationship(exponential decay model)between 95–105%of the relative yield and topsoil nitrate N,available P,and available K contents at wheat harvest from 60 field experiments,the topsoil critical nutrient values were determined as 34.6,15.6,and 150 mg kg^(-1)for soil nitrate N,available P,and available K,respectively.Then,based on five groups of relative yield(>125%,115–125%,105–115%,95–105%,and<95%)and the model,the five groups of topsoil critical nutrient levels and fertilization coefficients(Fc)were determined.Finally,we proposed a new method for calculating the recommended fertilizer input rate as:Fr=Gy×Nr×Fc,where Fr is the recommended fertilizer(N/P/K)input rate;Gy is the potential grain yield;Nr is the N(N_(rN)),P(N_(rP)),and K(N_(rK))nutrient requirements for wheat to produce 1,000 kg of grain;and Fc is a coefficient for N(N_c)/P(P_c)/K(K_c)fertilizer.A 2-year validated experiment confirmed that the new method reduced N fertilizer input by 17.5%(38.5 kg N ha^(-1))and P fertilizer input by 43.5%(57.5 kg P_(2)O_(5) ha^(-1))in northern China and did not reduce the wheat yield.This outcome can significantly increase the farmers’benefits(by 7.58%,or 139 US$ha^(-1)).Therefore,this new recommended fertilization method can be used as a tool to guide N,P,and K fertilizer application rates for dryland wheat production.

Plastic mulch increases dryland wheat yield and water-use productivity,while straw mulch increases soil water storage

Amplifying drought stress and high precipitation variability impair dryland wheat production.These problems can potentially be minimized by using plastic mulch(PM)or straw mulch(SM).Therefore,wheat grain yield,soil water storage,soil temperature and water-use productivity of PM and SM treatments were compared with no mulch(CK)treatment on dryland wheat over a period of eight seasons.Compared to the CK treatment,PM and SM treatments on average significantly increased grain yield by 12.6 and 10.5%,respectively.Compared to the CK treatment,SM treatment significantly decreased soil daily temperature by 0.57,0.60 and 0.48℃ for the whole seasons,growing periods and summer fallow periods,respectively.In contrast,compared to the CK treatment,PM treatment increased soil daily temperature by 0.44,0.51 and 0.27℃ for the whole seasons,growing periods and summer fallow periods,respectively.Lower soil temperature under SM allowed greater soil water storage than under PM.Soil water storage pre-seeding was 17%greater under the SM than under the PM treatment.Soil water storage post-harvest was similar for the PM and SM treatments,but evapotranspiration was 4.5%higher in the SM than in the PM treatment.Consequently,water-use productivity was 6.6%greater under PM than under the SM treatment.Therefore,PM treatment increased dryland wheat yield and water-use productivity,while straw mulch increased soil water storage.

Mott Gap Filling by Doping Electrons through Depositing One Sub-Monolayer Thin Film of Rb on Ca_(2)CuO_(2)Cl_(2)

Understanding the doping evolution from a Mott insulator to a superconductor probably holds the key to resolve the mystery of unconventional superconductivity in copper oxides. To elucidate the evolution of the electronic state starting from the Mott insulator, we dose the surface of the parent phase Ca_(2)CuO_(2)Cl_(2) by depositing Rb atoms, which are supposed to donate electrons to the CuO_(2) planes underneath. We successfully achieved the Rb sub-monolayer thin films in forming the square lattice. The scanning tunneling microscopy or spectroscopy measurements on the surface show that the Fermi energy is pinned within the Mott gap but close to the edge of the charge transfer band. In addition, an in-gap state appears at the bottom of the upper Hubbard band(UHB), and the Mott gap will be significantly diminished. Combined with the Cl defect and the Rb adatom/cluster results, the electron doping is likely to increase the spectra weight of the UHB for the double occupancy. Our results provide information to understand the electron doping to the parent compound of cuprates.

新时代高职院校劳动教育体系建设的价值意蕴与路径选择

高职院校劳动教育体系是学校、政府、行业、企业等多元主体,围绕立德树人根本任务和高职院校专业人才培养目标,在一定的价值取向和观念的指导下,遵循当代大学生成长与发展规律,秉持一定的运行规则和运行方式,形成的相互关联、相互作用、相互协调的劳动教育系统建制。新时代高职院校劳动教育体系建设,既是对国家经济社会发展需求的积极回应,也是我国高职院校走向内涵式发展与培养高素质技术技能型人才的内在需要。研究发现,部分高职院校在劳动教育实施过程中,存在课程体系设计不完善、师资队伍配备不充足、评价机制不健全等现实困境。为此,在新时代,高职院校劳动教育体系建设要重点关注师资体系、课程体系、评价体系的整体谋划与协同推进。要构建高职院校劳动教育体系亟须打造劳动教育课程体系,将劳动教育贯穿于学生成长的全过程;完善劳动教育师资体系,全面推动劳动教育教学团队建设;优化劳动教育评价体系,明确劳动教育的评价改革方向。

Cascaded Model Predictive Control of Six-phase Permanent Magnet Synchronous Motor with Fault Tolerant Ability

In the field of high-power electric drives, multiphase motors have the advantages of high power-density, excellent fault tolerance and control flexibility. But their decoupling control and modulation process are much more complicated compared with three-phase motors due to the increased degree of freedom. Finite control set model predictive control can reduce the difficulties of controlling six-phase motors because it does not require modulation process. In this paper, a cascaded model predictive control strategy is proposed for the optimal control of high-power six-phase permanent magnet synchronous motors. Firstly, the current prediction model of torque and harmonic subspaces are established by decoupling the six-phase spatial variables. Secondly, a cascaded cost function with fault-tolerant capability is proposed to eliminate the weighting factor in the cost function. And finally, the proposed strategy is demonstrated through theoretical analysis and experiments. It is validated that the proposed method is able to maintain excellent steady-state control accuracy and fast dynamic response while significantly reduce the control complexity of the system. Besides, it can easily achieve fault-tolerant operation under open-phase fault.

Systematic principles of surrounding rock control in longwall mining within thick coal seams

Effective surrounding rock control is a prerequisite for realizing safe mining in underground coal mines.In the past three decades, longwall top-coal caving mining(LTCC) and single pass large height longwall mining(SPLL) found expanded usage in extracting thick coal seams in China. The two mining methods lead to large void space left behind the working face, which increases the difficulty in ground control.Longwall face failure is a common problem in both LTCC and SPLL mining. Such failure is conventionally attributed to low strength and high fracture intensity of the coal seam. However, the stiffness of main components included in the surrounding rock system also greatly influences longwall face stability.Correspondingly, surrounding rock system is developed for LTCC and SPLL faces in this paper. The conditions for simultaneous balance of roof structure and longwall face are put forward by taking the stiffness of coal seam, roof strata and hydraulic support into account. The safety factor of the longwall face is defined as the ratio between the ultimate bearing capacity and actual load imposed on the coal wall.The influences provided by coal strength, coal stiffness, roof stiffness, and hydraulic support stiffness,as well as the movement of roof structure are analyzed. Finally, the key elements dominating longwall face stability are identified for improving surrounding rock control effectiveness in LTCC and SPLL faces.

Neuroprotective effects of the immunodepressant FTY720 on caspase-3 expression and neural apoptosis in a rat model of acute spinal cord injury

BACKGROUND：Studies on the immunodepressant FTY720 have primarily focused on organ transplantation and autoimmune disease therapy.However,the effects on caspase-3 expression and neural apoptosis following acute spinal cord injury remain uncertain.OBJECTIVE：To elucidate the underlying mechanism of the immunodepressant FTY720 to alleviate spinal cord injury by inhibiting expression of caspase-3 and neural apoptosis.DESIGN,TIME AND SETTING：A randomized,controlled,animal experiment was performed at Central Laboratory of the Second Affiliated Hospital of Dalian Medical University from April to July 2009.MATERIALS：FTY720 was provided by Wuhan Yuancheng Technology Developing,China.METHODS：A total of 120 Sprague Dawley rats were randomly assigned to sham-surgery,model,and FTY720 groups.Spinal cord injury at the T9-10 segment was induced in model groups using the free-fall method.Following establishment of spinal cord injury at the T9-10 segment in the FTY720 group,rats were treated with an intragastric injection of 0.3 mL saline-diluted FTY720 （3 mg/kg）.MAIN OUTCOME MEASURES：At 6,12,24,48,and 72 hours following spinal cord injury,caspase-3 expression was detected using streptavidin-peroxidase immunohistochemistry,and neural apoptosis was detected using the TUNEL method.RESULTS：Positive caspase-3 expression and neural apoptosis was not observed in the sham-surgery group at the various time points.The number of apoptotic cells increased with time after acute spinal cord injury,peaked at 24 hours following injury,and then gradually reduced.However,neural apoptosis remained at a high level.Caspase-3 expression positively correlated with neural apoptosis （r= 0.864,P〈 0.05）.Caspase-3 expression and neural apoptosis significantly decreased following FTY720 therapy （P〈 0.05）.CONCLUSION：FTY720 significantly reduced caspase-3 expression and neural apoptosis in a rat model of acute spinal cord injury.

Effect of microstructure evolution on mechanical property of extruded Mg-12Gd-2Er-1Zn-0.6Zr alloys

The microstructure evolution of as-cast,as-extruded and peak-aged Mg-12Gd-2Er-1Zn-0.6Zr alloys were investigated by Optical Microscope(OM),X-ray Diffraction(XRD),Scanning Electron Microscope(SEM)and Transmission Electron Microscope(TEM).The mechanical performance was also tested by tensile test at room temperature in the present study.The results indicated that the lamellar 14H-LPSO structure formed during the solid solution process at 793 K for 24 h,and also existed after hot extrusion process.The dynamic recrystallization(DRX)occurred during hot extrusion.The DRXed fine grain size was∼5μm.Meanwhile,some un-DRXed grains contained LPSO structure had a roughly orientation along the extrusion direction.The tensile test result showed that the as-extruded alloy had a better elongation of 14%due to fine DRXed grain and fiber-like un-DRXed with LPSO structure attributed to the high elongation.Because of the precipitation of theβ′-phase,the ultimate tensile strength(UTS)and yield tensile strength(YTS)increased up to 415 MPa(UTS)and 374 MPa(YTS),respectively.

Fibrinogen-like protein 2 expression correlates with microthrombosis in rats with type 2 diabetic nephropathy

Fibrinogen-like protein 2 （fgl2）, a novel prothrombinase, is involved in microthrombosis. We examined fgl2 expression in the glomerular and tubulointerstitial capillaries and its correlation with microthromsis in rats with streptozocin-induced type 2 diabetic nephropathy. Our RT-PCR and immunoblotting analysis showed that fgl2 mRNA and protein levels were increased in microvascular endothelial cells of the glomeruli and renal interstitia at week 19 and became significantly elevated with the development of diabetic nephropathy （P 〈 0.01）. Fgl2 was not or only weakly expressed in the renal tissues of normal rats. Furthermore, a direct significant correlation （r = 0.543, P 〈 0.01） was found between fgl2 expression and microthrombotic capillaries in the renal tissues. Enzyme linked immunosorbent assays （ELISA） additionally showed that circulating TNF-α levels in rats with type 2 diabetes were significantly elevated and closely correlated with fgl2 expression （r = 0.871, P 〈 0.01）. Our results suggest that fgl2 may activate renal microthrombosis, thus contributing to glomerular hypertension and renal ischemia.

Transgenic analyses of TGIF family proteins in Drosophila imply their role in cell growth

TG-interacting factors （TGIFs） belong to a family of TALE-homeodomain proteins including TGIF, TGIF2, and TGIF2LX/Y （TGIF2 like on X or Y chromosome） in human. They potentially play important functions in various tissues during development. Mutations in TGIF are frequently associated with malformation of forebrain and facial structures; TGIF2 proteins are over-expressed in many ovarian cancer cell lines; and TGIF2LX/Y are specifically expressed in adult testis. The molecular functions of these proteins have been investigated mostly in cultured cells. TGIF and TGIF2 have been found as transcriptional repressors that modulate TGF-beta signaling. However these findings are far from sufficient to explain their mutant phenotypes or expression patterns, and the functions of TGIF2LX/Y have never been reported. Here we use Drosophila as a model system to explore the functions of TGIF family proteins in vivo. We observed in fly tissues such as fat body, epithelia, and neuronal cells, that expressing human TGIF2 or human TGIF2LX generally inhibited cell growth in size and number. Co-expressing Drosophila Myc, Cyclin E, or human c-MycS partially rescued the growth inhibition induced by human TGIFs, whereas activated insulin pathway signaling did not. Taken together, we provide in vivo evidence for the potential functions of human TGIF2 and TGIF2LX in growth control. Additionally, we confirmed that Drosophila TGIFs are transcriptional activators by assaying their activities in spermatogenesis.

Fabrication of poly(vinylidene fluoride) membrane via thermally induced phase separation using ionic liquid as green diluent

Ionic liquid(IL),1-butyl-3-methylimidazolium hexafluorophosphate([BMIM]PF6)as a new and environmentally friendly diluent was introduced to prepare poly(vinylidene fluoride)(PVDF)membranes via thermally induced phase separation(TIPS).Phase diagram of PVDF/[BMIM]PF6 was measured.The effects of polymer concentration and quenching temperature on the morphologies,properties,and performances of the PVDF membranes were investigated.When the polymer concentration was 15 wt%,the pure water flux of the fabricated membrane was up to nearly 2000 L·m-2·h-1,along with adequate mechanical strength.With the increasing of PVDF concentration and quenching temperature,mean pore size and water permeability of the membrane decreased.SEM results showed that PVDF membranes manufactured by ionic liquid(BMIm PF6)presented spherulite structure.And the PVDF membranes were represented asβphase by XRD and FTIR characterization.It provides a new way to prepare PVDF membranes with piezoelectric properties.

Membranes for extracorporeal membrane oxygenator(ECMO): History,preparation, modification and mass transfer

Extracorporeal membrane oxygenator(ECMO) has been in development for nearly 70 years, and the oxygenator has gone through several generations of optimizations, with advances from bubble oxygenators to membrane oxygenators leading to more and more widespread use of ECMO. Membrane is the core of a ECMO system and the working mechanism of membrane oxygenator depends on the membrane material,from PDMS flat membrane to PMP hollow fiber membrane, which have experienced three generations.Blood compatibility on the surface of the membrane material is very vital, which directly determines the use duration of the oxygenator and can reduce the occurrence of complications. The mechanism of mass transfer is the basis of oxygenator operation and optimization. This review summarizes the membrane development history and preparation technology, modification approaches and mass transfer theory in the process of oxygen and blood exchange. We hoped that this review will provide more ideas for the study of gas blood exchange membrane.

Effects of trace Ca/Sn addition on corrosion behaviors of biodegradable Mg-4Zn-0.2Mn alloy

The effects of alloying elements of Ca/Sn on corrosion behaviors of the as-cast Mg-4Zn-0.2Mn alloy were investigated by immersion tests and electrochemical methods.The results indicated that the average corrosion rate value of the Mg-4Zn-0.2Mn-Ca alloy was∼0.31 mm/year in Hank’s physiological solution for 40 days,and corrosion resistance increased for the specimens containing Ca element rather than that containing Sn because of the higher breakdown potential value,lower current density and deactivated corrosion rate,which was ascribed to a formation of the uniformly distributed Mg-Zn-Ca ternary phase.

Full Length Article Effect of trace addition of al on microstructure,texture and tensile ductility of Mg-6Zn-0.5Er alloy

The effects of trace addition of Al on the microstructure and mechanical properties of the as-extruded Mg-6Zn-0.5Er alloy were investigated in the present investigation.The results showed that the trace addition of Al affected the mechanical properties significantly.The elongation of the extruded alloy was improved markedly from 17 to 25%with the trace addition of Al.It is suggested that the improvement of ductility was mainly attributed to the modification of basal texture of the as-extruded alloy,resulting from the complete dynamic recrystallization due to the trace addition of Al.In addition,the existence of the complete dynamic recrystallization led to an obvious increase in the number fraction of high angle grain boundaries,the average misorientation angle and Schmid factors for the(0001)1120 slip,which also have contributed to the improvement of ductility.

Insight into fouling behavior of poly(vinylidene fluoride)(PVDF)hollow fiber membranes caused by dextran with different pore size distributions

Membrane fouling is the key problem that occurs in membrane process for water treatment. However, how membrane microstructure influences the fouling behavior is still not clear. In this study, fouling behavior caused by dextran was deeply and systematically investigated by employing four poly（vinylidene fluoride） （PVDF） membranes with different pore sizes, ranging from 24 to 94 nm. The extent of fouling by dextran was accurately characterized by pore reduction, flux decline, and the change of critical flux. The result shows that membrane with the smallest pore size of 24 nm experienced the smallest fouling rate and the lowest fouling extent. As the membrane pore size increased, the critical flux ranges were 105-114, 63-73, 38-44 and 34- 43 L. m 2. h t, respectively. The critical flux and fouling resistances indicated that the fouling propensity in- creases with the increase of membrane pore size. Two pilot membrane modules with mean pore size of 25 nm and 60 nm were applied in membrane filtration of surface water treatment. The results showed that serious ir- reversible membrane fouling occurred on the membrane with pore size of 60 nm at the permeate flux of 40.5 L.m 2.h 1. On the other hand, membrane with pore size of 25 nm exhibited much better anti-fouling per- formance when permeate flux was set to 40.5, 48 and 60 L-m 2-h- 1.

Application of an antibody chip for screening differentially expressed proteins during peach ripening and identification of a metabolon in the SAM cycle to generate a peach ethylene biosynthesis model

Peach(Prunus persica)is a typical climacteric fruit that produces ethylene rapidly during ripening,and its fruit softens quickly.Stony hard peach cultivars,however,do not produce large amounts of ethylene,and the fruit remains firm until fully ripe,thus differing from melting flesh peach cultivars.To identify the key proteins involved in peach fruit ripening,an antibody-based proteomic analysis was conducted.A mega-monoclonal antibody(mAb)library was generated and arrayed on a chip(mAbArray)at a high density,covering~4950 different proteins of peach.Through the screening of peach fruit proteins with the mAbArray chip,differentially expressed proteins recognized by 1587 mAbs were identified,and 33 corresponding antigens were ultimately identified by immunoprecipitation and mass spectrometry.These proteins included not only important enzymes involved in ethylene biosynthesis,such as ACO1,SAHH,SAMS,and MetE,but also novel factors such as NUDT2.Furthermore,protein–protein interaction analysis identified a metabolon containing SAHH and MetE.By combining the antibody-based proteomic data with the transcriptomic and metabolic data,a mathematical model of ethylene biosynthesis in peach was constructed.Simulation results showed that MetE is an important regulator during peach ripening,partially through interaction with SAHH.

Flexible PEDOT:PSS nanopapers as“anion-cation regulation”synergistic interlayers enabling ultra-stable aqueous zinc-iodine batteries

Aqueous zinc-iodine(Zn-I_(2))batteries are promising candidates for low-cost grid-scale energy storage systems.However,the long-term stability and energy density of the Zn-I_(2)batteries are largely hindered by the lack of feasible and scalable methods that coherently suppress polyiodide shuttling and Zn dendrites growth,especially at high current densities.Herein,a flexible,thin and lightweight poly(3,4-ethy lenedioxythiophene):polystyrene sulfonate(PEDOT:PSS)nanopaper is designed as an“anion-cation regulation”synergistic interlayer to tackle the above issues.The PEDOT:PSS interlayer exhibits a 3D nanofibrous network with uniformly distributed mesopores,abundant polar groups and intrinsic conductivity,which renders an even Zn^(2+)flux at Zn anode and facilitates homogeneous current distributions at I_(2)cathode.Meanwhile,such interlayer can act as physiochemical shield to enhance the utilization of I_(2)cathode via the coulombic repulsion and chemical adsorption effect against polyiodide shuttling.Thus,long-term dendrite-free Zn plating/stripping is achieved at simultaneous high current density and high areal capacity(550 h at 10 m A cm^(-2)/5 m Ah cm^(-2)).Zn-I_(2)batteries harvest a high capacity(230 m Ah g^(-1)at 0.1 A g^(-1))and an ultralong lifespan(>20000 cycles)even at 10 A g^(-1).This work demonstrates the potential use of the multifunctional interlayers for Zn-I_(2)battery configuration innovation by synergistic regulation of cations and anions at the electrodes/electrolyte interface.

Innovative hydrophobic/hydrophilic perfluoropolyether(PFPE)/polyvinylidene fluoride(PVDF)composite membrane for vacuum membrane distillation

Though membrane distillation(MD)has gained more and more attention in the field of desalination,the wetting phenomenon was still a non-negligible problem.In this work,a method combined dip-coating and UV in situ polymerization for preparing hydrophobic/hydrophilic perfluoropolyether(PFPE)/polyvinylidene fluoride composite membranes.This composite membrane consisted of a top thin hydrophobic coating layer and hydrophilic substrate membrane.In terms of anti-wetting properties,contact angle and liquid entry pressure of all composite membranes(except for those based on 0.45μm)exceeded 160°and 0.3 MPa,respectively.In particular,the desalination performance was tested in vacuum membrane distillation tests by feeding 3.5%(mass)saline solution(NaCl)at 60℃.The composite membranes with larger support pore size and lower PFPE content had higher membrane distillation flux.And for stability tests(testing the 0.22μm membrane coated by 5%(mass)PFPE),the highest MD flux29.08 kg·m^(-2)·h^(-1) and stable salt rejection(over 99.99%)during the period.Except that,the effects of coating material concentration and pore sizes of substrate membrane were also investigated for surface morphology and topography,porosity,mechanical strength and pore size characteristics.This work provided a simple and effective alternative to prepare excellent hydrophobic composite membranes for MD applications.