学术之星最终版本

合集下载

1-s2.0-S0264127516312965-main

Optimizing matrix and ﬁber/matrix interface to achieve combination of strength,ductility and toughness in carbon nanotube-reinforced carbon/carbon compositesLei Feng,Kezhi Li ⁎,Bei Xue,Qiangang Fu,Leilei Zhang ⁎State Key Laboratory of Solidi ﬁcation Processing,Carbon/Carbon Composites Research Center,Northwestern Polytechnical University,Xi'an,710072,ChinaH I G H L I G H T S•Both matrix and ﬁber/matrix interface of carbon/carbon composites were opti-mized.•Radial carbon nanotube (CNT)was grown on carbon ﬁbers (CF)to strength-en matrix.•Pyrocarbon layer was introduced be-tween CF and CNT/matrix to optimize interface.•Optimal designs endowed composite with improved strength,ductility and toughness.G R A P H I C A L A B S T R A CTa b s t r a c ta r t i c l e i n f o Article history:Received 2July 2016Received in revised form 2October 2016Accepted 3October 2016Available online 5October 2016The direct attachment of carbon nanotubes (CNTs)on carbon ﬁbers (CFs)always leads to a decrease of ﬁber-dominated properties (e.g.,ﬂexural strength)and a brittle fracture behavior of C/Cs,although the matrix-domi-nated properties (e.g.,compressive strength and interlaminar shear strength (ILSS))exhibit an obvious enhance-ment.To achieve the combination of mechanical strength,ductility and toughness in C/Cs,in this work,efforts were spent on simultaneously optimizing the matrix and ﬁber/matrix (F/M)Ts with radial orienta-tion were grown onto the CFs by double-injection chemical vapor deposition to modify the microstructure of ma-trix.Pyrocarbon was deposited on the surface of CFs before CNT growth to protect CFs and to weaken interfacial strength between CFs and CNT/matrix.These optimal designs create strengthening and toughness mechanisms such as crack de ﬂection and long pullout of CFs in the failure process of composites,which endow C/Cs with im-proved ﬂexural strength of 31.5%,ﬂexural ductility of 118%,compressive strength of 81.5%and ILSS of 82%,ac-companied by a clear change from brittle fracture to pseudo-plastic fracture during ﬂexural test.This work may provide a meaningful way to not only enhance both the ﬁber-and matrix-dominated strength but to sub-stantially improve the ductility and toughness of C/Cs.©2016Elsevier Ltd.All rights reserved.Keywords:Carbon nanotubesCarbon/carbon composites Interface Strength Toughness1.IntroductionDesign of high-performance structural engineering carbon/carbon composites (C/Cs)is driven by optimizing combinations of mechanicalMaterials and Design 113(2017)9–16⁎Corresponding authors.E-mail addresses:likezhi@ (K.Li),zhangleilei@ (L.Zhang)./10.1016/j.matdes.2016.10.0060264-1275/©2016Elsevier Ltd.All rightsreserved.Contents lists available at ScienceDirectMaterials and Designj o u r n a l h o me p a g e :ww w.e l s e v i e r.c o m /l o c a t e /m a t d e sproperties such as strength,ductility,toughness and requirements for stability and non-catastrophic failure during service[1,2].C/Cs exhibits high speciﬁc strength and modulus,however,they have weak compres-sion and interlaminar properties,lack ductility and toughness,and al-ways fail in an apparently brittle manner in unconstrained loading geometries[3–5].Recently,the huge interest in incorporating carbon nanotubes (CNTs)into structural composites have been stimulated by virtue of their extraordinary intrinsic properties,such as ultrahigh strength,ex-cellent electrical and thermal conductivities[6,7].These outstanding mechanical and physical properties,in combination with their unique 1D nanostructures with high speciﬁc surface areas,allow for efﬁcient tailoring of both matrix microstructure andﬁber/matrix(F/M)interface state[8,9].For the incorporation of CNTs into composite structures,the general trend has been focused on in situ-growth of CNTs[10–12]or attaching CNTs to the carbonﬁbers(CFs)[13–15].Unlike attracting CNTs which trend to lie in the plane ofﬁber surface and thus only pro-vide one-side reinforcement to the C/Cs(just at F/M interface area), growing CNTs on the surface of CFs by catalytic chemical vapor deposi-tion(CVD)has many advantages in terms of controllability of size and orientation of CNTs,particularly a radial orientation that allows for si-multaneous reinforcements to the matrix and F/M interface[16].Excit-ing increases in matrix-dominated properties(e.g.,compressive strength and interlaminar shear strength)of C/Cs have been observed by growing CNTs onto carbonﬁbers[17–19].Nevertheless,there still exit some critical issues regarding the C/Cs reinforced with CVD-grown CNTs.Firstly,due to the potential damage(dissolution of metal catalysts into carbon,local oxidation and gasiﬁcation)of the CFs during the growth reaction[20,21],and the difﬁculty of controlling the orienta-tion and uniformity of the grafted CNTs on CFs[16,22,23],the studies on the enhancements both inﬁber-and matrix-dominated strengths of C/ Cs have rarely been reported.Secondly and more importantly,the direct attachment of CNTs onto CF surface always result in strong F/M interfa-cial bonding and thus obstructs the crack deﬂection along the axis of CFs [17,23–25],which leads to the failure ofﬁber pullout as an effective strengthening and toughening mechanism.There will be little or no property enhancement in the ductility and toughness expected in such a mode of composite failure[26,27].If CNT-reinforced C/Cs is to re-place C/Cs in industries,it is necessary to achieve the combination of global strength,ductility and toughness in C/Cs.Over the past few de-cades,however,few efforts have been spent on this issue.To improve the comprehensive mechanical performance of CNT-re-inforced C/Cs,the substantial problem and great challenge are how to moderate the F/M interfacial bonding so that it is neither too strong nor too weak and how to supply effective reinforcements to the carbon matrix without degrading theﬁber strength.In this work,a thin pyrocarbon(PyC)interface layer was deposited on the surface of CFs by chemical vapor inﬁltration(CVI)technique to optimize the F/M in-terfacial bonding,whilst preventing the dissolution of metal catalysts into CFs occurred during the subsequent growth of CNTs.Afterwards, double-injection CVD(DICVD)technique was developed to grow radial-ly-aligned CNTs on PyC-coated CFs.The schematic of this manufacturing process is depicted in Fig.1.The hybridﬁber preforms were then desiﬁned by CVI technique to obtain theﬁnal CNT-reinforced C/Cs. Three-point bending,compression and interlaminar shearing tests were applied to examine the effect of these optimal designs on the me-chanical properties of C/Cs.2.Experimental2.1.Raw materialsCarbon felts(bulk density0.2g/cm3,ﬁber diameters6–8μm,Yixing Tianniao Co.Ltd.,China)used in this work were fabricated by alterna-tively overlapping layers of randomly oriented shortﬁber bundles with needle-punching step-by-step.2.2.Deposition of PyC interface layer on CFs and the growth of CNTsCarbon felts wereﬁrstly deposited with an interface layer of PyC by isothermal CVI technology,which was carried out at1080°C using ﬂowing mixture of CH4(40L/h)and N2(160L/h)under the ambient pressure.The growth of CNTs in carbon felts was conducted by DICVD technique using FeSO4·6H2O as catalyst precursor.Incipient wetness technique was applied to introduce catalysts into felts using distilled water as solvent.Afterwards,they were placed in a CVD reactor and heated to750°C under Arﬂowing.At the growth temperature,xylene as the hydrocarbon source was injected into the reactor through a thin tube via a syringe.Ethylenediamine as the growth promoter wasﬁlled in another syringe and was injected separately from the same side for the xylene injection.The ratio of injection rates of xylene and ethylenediamine was8:1.The Ar/H2(2/1)gas mixture was used as the carrier gas with aﬂow rate of600sccm.The growth time was2h. The direct growth of CNTs in carbon felts without PyC interface layer was also performed by DICVD technique under identical growth condi-tions.The volume fractions of CNTs in carbon felts with and without PyC interface layer were approximately1.3%.posite preparation and mechanical property testsThe densiﬁcation was carried out by isothermal CVI technique for 150h under the conditions described in section2.2.The C/Cs containing both the PyC interface layer and CNTs were denoted as CNT-PyC-C/Cs, while the C/Cs containing only CNTs were denoted as CNT-C/Cs.The Fig.1.Schematic of depositing PyC interface layer on CFs and followed by growth of radial CNTs by DICVD to maintainﬁber strength,optimize F/M interface and strengthen matrix of C/Cs. 10L.Feng et al./Materials and Design113(2017)9–16densities of pure C/Cs,CNT-C/Cs and CNT-PyC-C/Cs were measured in the range of 1.64–1.67g/cm 3.The sizes of samples for bending tests were machined into 50mm ×8mm ×4mm.The support span for bend-ing tests was 40mm.To study the quasi-ductile fracture behavior of the composites,a ductility factor was introduced.It was calculated from the ratio of the secant modulus (the slope of the line from the origin to the stress at failure in the ﬂexural stress-strain curve)to the elastic modulus [28].The samples used for compression test and interlaminar shearing test were machined into the sizes of 5mm ×5mm ×4mm.The numbers of samples for bending,compression and shearing tests were not less than 5.All the tests were carried out on a universal testing machine (CMT5304)at a constant speed of 0.5mm/min.2.4.CharacterizationThe morphologies and microstructures of grafted CNTs were exam-ined by scanning electrical microscopy (SEM,JSM-6700)operated at 15kV and transmission electrical microscopy (TEM,Tecnai F30G 2)op-erated at 200kV,respectively.Microstructure of the matrix PyC was in-vestigated using polarized light microscopy (PLM,Leica DMLP).The Raman spectrum was recorded on a Renishaw Invia RM200using aninVia micro-Raman spectrometer with an Ar ion laser of 514.5nm wavelength at room temperature.3.Results and discussion3.1.Radially-aligned CNTs grafted on CFs with and without PyC coating Fig.2a shows the surface SEM image of the CFs coated with a homog-enous PyC interface layer with a thickness of about 200nm (Fig.2b).After the growth process by DICVD,the CFs without (Fig.2c)and with (Fig.2d)PyC interface layer are uniformly covered with CNTs.The CNTs exhibit radial grafting morphologies,indicating that the DICVD technique has good repeatability for growing radial CNTs on different carbonaceous substrates.These radial nanotubes extend into the space among ﬁbers capability of providing ef ﬁcient reinforcements both to the interlaminar and intralaminar matrix [29].Observation of the cross-section of hybrid ﬁbers presents the detailed information about the CNT length ranging from 4to 7μm (Fig.2e).TEM investigation (Fig.2f)reveals that the products are hollow nanotubes with smooth walls and a typical outer diameter of about 300nm.And the inner diam-eter and tube-wall thickness are about 200nm and 50nm,respectively.Fig.2.SEM images:(a)surface and (b)cross-section of PyC-coated CFs;(c)surface of radially-aligned CNTs grafted on CFs;(d)surface and (e)cross-section of radially-aligned CNTs grafted on PyC-coated CFs.(f)TEM image of an individual CNT and its high resolution TEM image (inset of f).11L.Feng et al./Materials and Design 113(2017)9–16High resolution TEM image (Fig.2f inset)presents that the CNTs have multi-walled structures and the graphitic sheets are parallel to the axial direction,exhibiting a good crystallinity.3.2.Microstructure of compositesThe polished transverse section of the C/Cs,CNT-C/Cs and CNT-PyC-C/Cs viewed by polarized light microscopy is shown in Fig.3.For C/Cs (Fig.3a),the PyC around CFs is in the shape of circular shell and has large grain size,long boundaries between interference colors and pro-nounced homocentric annular cracks.By contrast,PyC in CNT-PyC-C/Cs (Fig.3b)and CNT-C/Cs (Fig.3b inset)demonstrates a different mor-phology.As for the CFs grafted with radial CNTs,the PyC will deposit around the nanotubes rather than directly on the surface of CFs (here,CNTs provide direct reinforcement to the matrix within the reach of nanotubes).Besides,it has been demonstrated in our previous work [30],where the CNTs can also affect the PyC out of the reach of nano-tubes by inducing the formation of spherical or cone-shaped PyC and then restricting their growing up (here,it can be called as “indirect rein-forcement ”).As a result,the consequent PyC is clearly different in mor-phology from that in pure C/Cs.As seen,the PyC in C/Cs containing CNTs exhibits small grain size,short boundaries between interference colors and no annular cracks.In addition,it is interesting to note that CFs in CNT-PyC-C/Cs present white outlines (labeled by arrows in Fig.3b)at-tributed to the presence of PyC interface layers.Fig.3c and d presents the Raman results of C/Cs and CNT-PyC-C/Cs (same with CNT-C/Cs),respectively.Intensity ratio of disorder-inducedD-peak and tangential G-peak is inversely proportional to the level of crystalline order and crystal size L a (in nm)[31].As stated in Table 1,the D:G intensity ratio,I D /I G ,is about 1.85for C/Cs and falls to approxi-mately 1.52for CNT-PyC-C/Cs,suggesting that PyC has a signi ﬁcant im-provement in crystallinity and meanwhile a big increase in L a after introducing radial CNTs.Axisymmetric peak broadening represents for large interplanar spacing d 002of carbon materials [32].As seen,both G-peak and D-peak of interlayer become sharper and more de ﬁned after introducing radial CNTs,which indicates that,the d 002value of PyC in CNT-PyC-C/Cs has a distinct decrease compared with that in C/Cs.As the crystalline order improves and crystal size increases,the bond density within the interlayer increases [33].High bond densities and few defects could lead to a signi ﬁcant increase in mechanical strength of PyC matrix.3.3.Mechanical properties of compositesFig.4presents the stress-strain curves of the three composites re-corded during bending test,compression test and shearing test.The de-tailed results of mechanical tests of three composites are listed in Table pared with C/Cs,CNT-PyC-C/Cs shows obvious improve-ment in ﬂexural strength,ﬂexural ductility,compressive strength and interlaminar shear strength (ILSS):31.5%in ﬂexural strength,118%in ﬂexural ductility,81.5%in compressive strength and 82%in ILSS.How-ever,the ﬂexural strength and ﬂexural ductility of CNT-C/Cs are de-creased by 14.5%and 73%,although the compressive strength and ILSS are increased by 67%and 115%,respectively.From the ﬂexuralstress-Fig.3.PLM images (a,b and inset)and Raman spectra (c,d)of the three composites:(a and c)C/Cs;(inset of b)CNT-C/Cs;(b and d)CNT-PyC-C/Cs (note:red points marked in a and b are the Raman detection positions).Table 1Raman testing data of C/Cs,and CNT-PyC-C/Cs (±values represent standard deviation).Composite FWHM of G-peak (cm −1)FWHM of D-peak (cm −1)I D /I GC/Cs84.41±0.21116.54±0.30 1.85±0.01CNT-PyC-C/Cs78.76±1.8288.62±1.341.52±0.0712L.Feng et al./Materials and Design 113(2017)9–16strain curves (Fig.4a),we can get the information regarding the fracture behavior of the three composites.For C/Cs and CNT-C/Cs,the ﬂexural stress-strain curves can be divided in two segments:linear rise and lin-ear decrease of stress.The stress suddenly drops leading to the cata-strophic failure of the samples as stress goes up to the peak value,which designates brittle fracture occurs in the two composites.By con-trast,CNT-PyC-C/Cs shows pronounced pseudo-plastic fracture behav-ior since the load decreases in a step-style rather than perpendicularly after the peak value.The stress-stain curve can be divided into three segments:linear rise of load,non-linear rise of load and stepped de-crease of load.The different segments correspond to three stages:ma-trix elastic deformation,appearing and propagating of destructive cracks among matrix,interfacial debonding and ﬁber pullout,respec-tively [34,35].It means that CNT-PyC-C/Cs does not rupture completely but only fractures partly,avoiding the catastrophic failure as the loading stress reaches to the maximum value,which indicates a signi ﬁcant im-provement in the fracture toughness [36,37].The observation from the compressive and shear stress-strain curves (Fig.4b and c)is that the compressive strength and ILSS of C/Cs can be signi ﬁcantly increased by grafting radial CNTs onto CFs,no matter whether the PyC interface layer is presented or not.From these results it is suggested that if we want to improve the global mechanical strength,ductility and tough-ness of C/Cs,it is necessary to simultaneously optimize both the matrix and F/M interface.When the ﬂexural stress is loaded on the composite samples,the strength of the composites is mainly depended on the strength of CFs.Fig.5shows the SEM images of ﬂexural fracture surfaces of the three composites.In Fig.5a,the fracture surface of C/Cs shows plenty of step-wise fractured PyC and very limited ﬁber pullout.These fracture steps result from the annular cracks that supply the paths for the spreading and link up of destructive cracks and then lead to the formation of step-wise PyC panels.Besides,the F/M interfacial bonding of C/Cs is loose with obvious gaps between CFs and PyC (Fig.5a inset).According to the observations from Fig.5a,the fracture process in C/Cs during bend-ing test can be described as follows:when the bending stress is loaded on the composite samples,destructive cracks will appear somewhere in matrix at the most critical ﬂaws,and then propagate along the annu-lar cracks leading to the delaminating of PyC;it is hard for the weak ma-trix and poor F/M interface to induce the de ﬂection of destructive cracks to propagate along ﬁber surface,which leads to the early failure of CFs since the CFs is dif ﬁcult to be hold on by matrix [38];as the stress further increases,these destructive cracks link up with each other and then the failure of composites occurs.The strength of CFs cannot be fully re ﬂected and thus the C/Cs exhibits brittle fracture with low fracture strength.As for CNT-C/Cs,the fracture surface is ﬂat and with nearly ab-sent of ﬁber pullout (Fig.5b).This fracture surface can be attributed to the strongly-enhanced cohesion in matrix and also the powerful me-chanical interlocking at F/M interface,which lead the destructive cracks to extend into and through the CFs without interfacial debonding (Fig.5b inset).Additionally,the degradation of tensile strength of CFs caused during the CNT growth process is also responsible for the degra-dation of ﬂexural strength of CNT-C/Cs [39].In contrast,CNT-PyC-C/Cs shows a stepwise fracture surface with abundant ﬁber pullouts (Fig.5c).Enlarged SEM image (Fig.5d)illustrates that the destructive cracks spread along the nano/μ-scale grain boundaries (labeled by red dotted lines).When the destructive cracks extend to the CFs,PyC inter-face layer plays a role in changing their direction and facilitates them spreading along the direction parallel to the ﬁber axis as much as possi-ble (as shown in Fig.5e,where exposed PyC interface layer on the pulled-out CFs can be clearly observed).The PyC interface layer protects CFs effectively and weakens the interfacial strength between CFs and CNT/PyC,leading to the long pull-out of CFs compared with brittle frac-ture of CFs without PyC interface layer.Therefore,the stress can be ef ﬁ-ciently transferred from the matrix to the CFs through the strengthened matrix and optimized F/M interface.Crack de ﬂection and ﬁber pullout require a great amount of fractured energy consumption during the fail-ure process [26,27,30,40],which in turn increase the ﬂexural strength and ductility of CNT-PyC-C/Cs and also make the ﬂexural stress release gently,resulting in the sliding region occurred in the ﬂexural stress-strain curve which corresponds to an improved fracture toughness.When the compressive stress is loaded on the composite samples,the compressive strength is mainly depended on the matrix cohesion.Fig.6presents the SEM images of compressive fracture surfaces of the three composites.The fracture surface of C/Cs shows ﬂat and no CFs exist on the surface (Fig.6a),implying that fracture primarily occurs as a typical delamination failure without crack de ﬂection during com-pression test (corresponding failure model is depicted in Fig.6a inset).High degree of matrix delaminating is the dominant mechanism for the delamination failure (Fig.6b).Enlarged SEM image (Fig.6c)clearly shows existing annular cracks provide main channels for the long-dis-tance extending of destructive cracks and then opening the plies.As for CNT-C/Cs (Fig.6d),the strongly-enhanced matrix ef ﬁciently im-pedes the propagation of destructive cracks in the interlaminar region (corresponding failure mode is shown in Fig.6d inset).The de ﬂected destructive cracks then turn to the intralaminar regions (Fig.6e)and di-rectly pass through the CFs by virtue of strong F/M interfacialbonding,Fig.4.Stress-strain curves of the three composites recorded during different mechanical tests:(a)ﬂexural test;(b)compression test;(c)Shearing test.Table 2Mechanical properties of C/Cs,CNT-C/Cs and CNT-PyC-C/Cs (±values represent standard deviation).Composite Flexural strength (MPa)Flexural ductility Compressive strength (MPa)Shear strength (MPa)C/Cs54±60.11±0.03195±1133±5CNT-C/Cs46±70.03±0.01326±1371±8CNT-PyC-C/Cs71±100.24±0.06354±1660±613L.Feng et al./Materials and Design 113(2017)9–16forming many ﬂat fractured surfaces (Fig.6f).But comparatively,CNT-PyC-C/Cs shows a rugged fracture surface with many exposed CFs (Fig.6g),indicating that the propagation direction of destructive cracks also changes mangy times during compression test (corresponding fail-ure mode is shown in Fig.6g inset).The optimized F/M interface induces the long-distance propagation of destructive cracks along the ﬁber sur-face rather than directly pass through the CFs occurred in CNT-C/Cs (Fig.6h and i).More energies are dissipated during this course,which in turn could explain the more pronounced increment in the compressive strength for CNT-PyC-C/Cs (that is 81.5%)than that of CNT-C/Cs (that is 67%).When the interlaminar shear stress is loaded on the composite sam-ples,the shear strength is mainly depended on both the matrix cohesion and F/M interfacial bonding strength.Fig.7presents the shearing frac-ture surface of three composites.As seen in Fig.8a,the smooth PyC shearing fracture surface suggests a serious matrix delaminating in C/Cs,which is similar to the failure mode observed in compression test.It can be thus said that for C/Cs the matrix cohesion is lowerthanFig.5.SEM images of the ﬂexural fracture surfaces of the three composites:(a and inset)C/Cs;(b and inset)CNT-C/Cs;(c –e)CNT-PyC-C/Cs.Fig.6.SEM images of the compressive fracture surfaces of the three composites:(a –c)C/Cs;(d –f)CNT-C/Cs;(g –i)CNT-PyC-C/Cs (insets are the failure modes of the composites during compression tests).14L.Feng et al./Materials and Design 113(2017)9–16F/M interfacial bonding strength.As for the CNT-C/Cs (Fig.8b),matrix delaminating is inhibited and abundant damaged CFs can be clearly ob-served in the shearing fracture surface,indicating that the interfacial strength between CFs and CNT/PyC is strong enough to generate a crack de ﬂection from CNT/PyC to CFs and thus leading to the cleaving of CFs.However,for the CNT-C/Cs (Fig.8c),the F/M interfacial bonding seems to be relatively weak compared with the strongly-enhanced ma-trix,according to the long-distance spreading of destructive cracks along CF surface.This observation provides direct evidence that the PyC interface layer weakens the interfacial bonding strength between CFs and CNT/PyC (Fig.8c inset).It also explains the reason why the in-crement in ILSS of CNT-PyC-C/Cs (that is 82%)is lower than that of CNT-C/Cs (that is 115%).In addition,CNT pullout has rarely been found in all the fracture surfaces of composite samples.Therefore,it can be said that the contribution of our CNTs to the high mechanical strengths of composites is mainly re ﬂected in strengthening the matrix.From the above analysis,the schematic modeling of the failure mecha-nisms of the three composites during loading process has been established,as shown in Fig.8.4.ConclusionsPyC deposited on the CF surface following the radial CNT growth en-ables F/M interface optimizing,matrix strengthening and minimum degradation to the ﬁber strength.SEM morphologies of fracture surfaces of failure composites reveal that the synergistic effects of strongly-en-hanced matrix and optimized F/M interface not only ef ﬁciently de ﬂects the propagation direction of destructive cracks,but also induces the long-distance spreading of destructive cracks along the surfaces of CFs,which signi ﬁcantly increase the ﬂexural strength,ﬂexural ductility,frac-ture toughness,compressive strength and ILSS of C/Cs.However,the speci ﬁc interfacial bonding strength between CFs and CNT/PyC as well as the effect of thickness of PyC interface layer on the mechanical perfor-mance of CNT-reinforced C/Cs are still unclear.Still and all,this work might open up a possibility to produce CNT-reinforced C/Cs with excel-lent mechanical strength,ductility and toughness to replace traditional C/Cs in industries.AcknowledgementsThis work has been supported by the Fundamental Research Funds for the Central universities under Grant No.3102014JCQ01030and “111”Project of China (B08040),and the Natural Science Foundation of China (Grant Nos.51521061and51502242).Fig.7.SEM images of the shearing fracture surfaces of the three composites:(a)C/Cs;(b)CNT-C/Cs;(c and inset)CNT-PyC-C/Cs.Fig.8.The failure mechanisms of the three composites during loading process (red lines represent propagation paths of the destructive cracks).15L.Feng et al./Materials and Design 113(2017)9–16References[1] E.Fitzer,L.M.Manocha,Carbon Reinforcements and Carbon/Carbon Composites,Christiane,Berlin,1998.[2]T.Windhorst,G.Blount,Carbon-carbon composites:a summary of recent develop-ments and applications,Mater Des.18(1997)11–15.[3]K.Anada,V.Gupta,The effect of processing conditions on the compressive and shearstrength of2-D carbon-carbon laminates,Carbon33(1995)739–748.[4]G.Savage,Carbon/Carbon Composites,Springer,London,1993.[5]X.H.Hou,H.J.Li,S.Y.Zhang,J.Shen,Interface-like fracture mechanism in pyrolyticcarbon matrix-based carbon–carbon composites,Mater.Lett.48(2001)117–120.[6]K.M.Liew,Z.X.Lei,L.W.Zhang,Mechanical analysis of functionally graded carbonnanotube reinforced composites:a review,Compos.Struct.120(2015)90–97. [7]J.N.Coleman,U.Khan,W.J.Blau,Y.K.Gun'Ko,Small but strong:a review of the me-chanical properties of carbon nanotube-polymer composites,Carbon44(2006) 1624–1652.[8]M.Sharma,S.Gao,E.Mäder,H.Sharma,L.Y.Wei,J.Bijwe,Carbonﬁber surfaces andcomposite interphases,Compos.Sci.Technol.102(2014)35–50.[9]Q.M.Gong,Z.Li,X.D.Bai,D.Li,J.Liang,The effect of carbon nanotubes on the micro-structure and morphology of pyrolytic carbon matrices of C–C composites obtained by CVI,Compos.Sci.Technol.65(2005)1112–1119.[10] E.T.Thostenson,W.Z.Li,D.Z.Wang,Z.F.Ren,T.W.Chou,Carbon nanotube/carbonﬁber hybrid multiscale composites,J.Appl.Phys.91(2002)6034–6037.[11]V.P.Veedu,A.Cao,X.Li,K.Ma,C.Soldano,S.Kar,P.M.Ajayan,M.N.Ghasemi-Nejhad,Multifunctional composites using reinforced laminate with carbon-nanotube for-ests,Nat.Mater.5(2006)457–462.[12]R.Li,chman,P.Florin,H.D.Wagner,B.L.Wardle,Hierarchical carbon nanotubecarbonﬁber unidirectional composites with preserved tensile and interfacial prop-erties,Compos.Sci.Technol.117(2015)139–145.[13] A.R.Boccaccini,J.Cho,J.A.Roether,B.J.C.Thomas,E.J.Minay,M.S.P.Shaffer,Electro-phoretic deposition of carbon nanotubes,Carbon44(2006)3149–3160.[14]T.Kamae,L.T.Drzal,Carbonﬁber/epoxy composite property enhancement throughincorporation of carbon nanotubes at theﬁber-matrix interphase-part I:the devel-opment of carbon nanotube coated carbonﬁbers and the evaluation of their adhe-sion,Compos Part A-Appl S43(2012)1569–1577.[15]L.Mei,X.He,Y.Li,R.Wang,C.Wang,Q.Peng,Grafting carbon nanotubes onto car-bonﬁber by use of dendrimers,Mater.Lett.64(2010)2505–2508.[16]H.Qian,E.S.Greenhalgh,M.S.P.Shaffer,A.Bismarck,Carbon nanotube-based hierar-chical composites:a review,J.Mater.Chem.20(2010)4751–4762.[17]L.Feng,K.Z.Li,Z.S.Si,Q.Song,H.J.Li,J.H.Lu,et al.,Compressive and interlaminarshear properties of carbon/carbon composite laminates reinforced with carbon nanotube-grafted carbonﬁbers produced by injection chemical vapor deposition, Mater.Sci.Eng.A626(2015)449–457.[18]Q.Song,K.Z.Li,H.L.Li,H.J.Li,C.Ren,Grafting straight carbon nanotube radially ontocarbonﬁbers and their effect on the mechanical properties of carbon/carbon com-posites,Carbon50(2012)3943–3960.[19]H.Y.Yu,J.H.Lu,Q.Song,K.Z.Li,H.J.Li,Q.G.Fu,et al.,Compressive properties of car-bon/carbon composites reinforced by carbon nanotubes with different orientations and lengths,Vacuum99(2014)76–79.[20]H.Qian,A.Bismarck,E.S.Greenhalgh,G.Kalinka,M.S.P.Shaffer,et al.,Hierarchicalcomposites reinforced with carbon nanotube graftedﬁbers:the potential assessed at the singleﬁber level,Chem.Mater.20(2008)1862–1869.[21]T.R.Pozegic,I.Hamerton,J.V.Anguita,W.Tang,P.Ballocchi,P.Jenkins,et al.,Lowtemperature growth of carbon nanotubes on carbonﬁbre to create a highly networked fuzzyﬁbre reinforced composite with superior electrical conductivity, Carbon74(2014)319–328.[22]J.Zhao,L.Liu,Q.Guo,J.Shi,G.Zhai,J.Song,et al.,Growth of carbon nanotubes on thesurface of carbonﬁbers,Carbon46(2008)380–383.[23]P.Xiao,X.F.Lu,Y.Q.Liu,L.L.He,Effect of in situ grown carbon nanotubes on thestructure and mechanical properties of unidirectional carbon/carbon composites, Mater.Sci.Eng.A528(2011)3056–3061.[24]Y.Y.Li,L.J.Guo,Q.Song,L.Li,J.H.Lu,K.Z.Li,et al.,Simultaneous improvements inﬂexural strength and ductility of carbon nanotube-doped carbon/carbon composites by depositing a pyrocarbon layer on carbonﬁbers,Ceram.Int.41(2015) 1943–1949.[25]K.Z.Li,L.Li,H.J.Li,Q.Song,J.H.Lu,Q.G.Fu,Electrophoretic deposition of carbonnanotubes onto carbonﬁber felt for production of carbon/carbon composites with improved mechanical and thermal properties,Vacuum104(2014)105–110. [26]M.Sakai,R.Matsuyama,T.Miyajima,The pullout and failure of aﬁber bundle in acarbonﬁber reinforced carbon matrix composite,Carbon38(2000)2123–2131. [27]M.Sakai,T.Miyajima,M.Inagaki,Fracture toughness andﬁber bridging of carbonﬁber-reinforced carbon matrix composites,Compos.Sci.Technol.40(1991) 231–250.[28] B.Reznik,M.Guellali,D.Gerthsen,Microstructure and mechanical properties of car-bon–carbon composites with multilayered pyrocarbon matrix,Mater.Lett.52 (2002)14–19.[29]S.S.Wicks,R.G.de villoria,B.L.Wardle,Interlaminar and intralaminar reinforcementof composite laminates with aligned carbon nanotubes,Compos.Sci.Technol.70 (2010)20–28.[30]L.Feng,K.Z.Li,Z.G.Zhao,H.J.Li,L.L.Zhang,J.H.Lu,et al.,Three-dimensional carbon/carbon composites with vertically aligned carbon nanotubes:providing direct and indirect reinforcements to the pyrocarbon matrix,Mater.Des.92(2016)120–128.[31]P.Mallet-Ladeira,P.Puech, C.Toulouse,M.Cazayous,N.Ratel-Ramond,P.Weisbecker,et al.,A Raman study to obtain crystallite size of carbon materials:a better alternative to the Tuinstra–Koenig law,Carbon80(2014)629–639.[32] A.Yoshida,Y.Kaburagi,Y.Hishiyama,Full width at half maximum intensity of the Gband in theﬁrst order Raman spectrum of carbon material as a parameter for graph-itization,Carbon44(2006)2333–2335.[33] C.A.Taylor,M.F.Wayne,W.K.S.Chiu,Heat treatment of thin carbonﬁlms and the ef-fect on residual stress,modulus,thermal expansion and microstructure,Carbon41 (2003)1867–1875.[34]X.Xiong,Y.L.Wang,Z.K.Chen,G.D.Li,Mechanical properties and fracture behaviorsof C/C composites with PyC/TaC/PyC,PyC/SiC/TaC/PyC multi-interlayers,Solid State Sci.11(2009)1386–1392.[35]H.Hatta,K.Suzuki,T.Shigei,S.Somiya,Y.Sawada,Strength improvement by densi-ﬁcation of C/C composites,Carbon39(2001)83–90.[36]H.L.Li,H.J.Li,J.H.Lu,C.Sun,Y.J.Wang,D.J.Yao,et al.,Improvement in toughness ofcarbon/carbon composites using multiple matrixes,Mater.Sci.Eng.A530(2011) 57–62.[37]G.Z.Xu,H.J.Li,R.C.Bai,J.Wei,Y.Q.Zhai,Inﬂuence of the matrix texture on the frac-ture behavior of2D carbon/carbon composites,Mater.Sci.Eng.A478(2008) 319–323.[38]J.Chen,P.Xiao,X.Xiong,The mechanical properties and thermal conductivity of car-bon/carbon composites with theﬁber/matrix interface modiﬁed by silicon carbide nanoﬁbers,Mater.Des.84(2015)285–290.[39]L.Feng,K.Z.Li,J.J.Sun,Y.J.Jia,H.J.Li,L.L.Zhang,Inﬂuence of carbon nanotube ex-tending length on pyrocarbon microstructure and mechanical behavior of carbon/ carbon composites,Appl.Surf.Sci.355(2015)1020–1027.[40]R.R.Naslain,The design of theﬁbre-matrix interfacial zone in ceramic matrix com-posites,Compos.Part A-Appl.S29(1998)1145–1155.16L.Feng et al./Materials and Design113(2017)9–16。

10.1007_s00253-010-2443-4

BIOTECHNOLOGICAL PRODUCTS AND PROCESS ENGINEERINGEffects of biotic and abiotic elicitors on cell growth and tanshinone accumulation in Salvia miltiorrhiza cell culturesJiang-Lin Zhao &Li-Gang Zhou &Jian-Yong WuReceived:7September 2009/Revised:6January 2010/Accepted:6January 2010/Published online:2March 2010#Springer-Verlag 2010Abstract This study examined the effects of biotic and abiotic elicitors on the production of diterpenoid tanshi-nones in Salvia miltiorrhiza cell culture.Four classes of elicitors were tested,heavy metal ions (Co 2+,Ag +,Cd 2+),polysaccharides (yeast extract and chitosan),plant response-signaling compounds (salicylic acid and methyl jasmonate),and hyperosmotic stress (with sorbitol).Of these,Ag (silver nitrate),Cd (cadmium chloride),and polysaccharide from yeast extract (YE)were most effective to stimulate the tanshinone production,increasing the total tanshinone content of cell by more than ten-fold (2.3mg g -1versus 0.2mg g -1in control).The stimulating effect was concentration-dependent,most significant at 25μM of Ag and Cd and 100mg l -1(carbohydrate content)of YE.Of the three tanshinones detected,cryptotanshinone was stimulat-ed most dramatically by about 30-fold and tanshinones I and IIA by no more than 5-fold.Meanwhile,most of the elicitors suppressed cell growth,decreasing the biomass yield by about 50%(5.1–5.5g l -1versus 8.9g l -1in control).The elicitors also stimulated the phenylalanine ammonia lyase activity of cells and transient increases in the medium pH and conductivity.The results suggest that the elicitor-stimulated tanshinone accumulation was a stress response of the cells.Keywords Salvia miltiorrhiza .Cell culture .Tanshinones .Elicitors .Stress responseIntroductionSalvia miltiorrhiza Bunge (Lamiaceae),called Danshen in Chinese,is a well-known and important medicinal plant because its root is an effective herb for treatment of menstrual disorders and cardiovascular diseases and for the prevention of inflammation (Tang and Eisenbrand 1992).As its Chinese name refers,Danshen root is characterized by the abundance of red pigments which are mainly ascribed to numerous diterpene quinones generally known as tanshinones,e.g.,tanshinone I (T-I),tanshinone-IIA (T-IIA),and T-IIB,isotanshinone I and II,and cryptotanshinone (CT).Tanshinones constitute a major class of bioactive compounds in S .miltiorrhiza roots with proven therapeutic effects and pharmacological activities (Wang et al.2007).Danshen in combination with a few other Chinese herbs is an effective medicine widely used for the treatment of cardiovascular diseases and used as an emergency remedy for coronary artery disease and acute ischemic stroke.According to WHO statistics,cardiovas-cular diseases are and will continue to be the number one cause of death in the world (www.who.int/cardiovascular_diseases ).It is of significance to develop more efficient means for the production of Danshen and its active constituents.Although field cultivation is currently the major produc-tion means for Danshen and most other plant herbs,plant tissue cultures provide more well-controlled and sustainable systems for efficient production of desired bioactive compounds of the herb.Plant tissue cultures are the most useful and convenient experimental systems for examiningJ.-L.Zhao :L.-G.Zhou (*)Department of Plant Pathology,China Agricultural University,Beijing 100193,China email:lgzhou@J.-Y .Wu (*)Department of Applied Biology and Chemical Technology,The Hong Kong Polytechnic University,Hung Hom,Kowloon,Hong Kong email:bcjywu@.hkAppl Microbiol Biotechnol (2010)87:137–144DOI 10.1007/s00253-010-2443-4various factors on the biosynthesis of desired products and for exploring effective measures to enhance their produc-tion.The importance of Danshen for traditional and modern medicines has promoted the long-lasting research interest in the development of tiorrhiza tissue cultures for production of bioactive compounds for more than two decades.In an early study,Nakanishi et al.(1983)induced several cell lines from plant seedlings and screened out a cell line capable of producing significant amounts of CT and another diterpene,ferruginol.In later studies,the group performed a fuller evaluation and optimization of the medium for cell growth and CT production and,eventually,derived an effective production medium with a simpler composition(ten components)than the original Murashige and Skoog(MS) medium(about20components),achieving a high CT yield of 110mg l-1(Miyasaka et al.1987).Many recent studies have been focused on hairy root cultures of tiorrhiza transformed by Agrobacterium rhizogenes(Hu and Alfermann1993;Chen et al.2001)and by our group (Zhang et al.2004;Ge and Wu2005;Shi et al.2007).Most of the bioactive compounds in medicinal plants belong to secondary metabolites which are usually less abundant than primary metabolites in the plants.Since the accumulation of secondary metabolites in plants is a common response of plants to biotic and abiotic stresses, their accumulation can be stimulated by biotic and abiotic elicitors.Therefore,elicitation,treatment of plant tissue cultures with elicitors,is one of the most effective strategies for improving secondary metabolite production in plant tissue cultures(Chong et al.2005;Smetanska2008).The most common and effective elicitors used in previous studies include the components of microbial cells especially poly-and oligosaccharides(biotic)and heavy metal ions, hyperosmotic stress,and UV radiation(abiotic),and the signaling compounds in plant defense responses such as salicylic acid(SA)and methyl jasmonate(MJ;Zhou and Wu2006;Smetanska2008).Some of these elicitors,yeast extract(mainly the polysaccharide fraction),silver ion Ag+, and hyperosmotic stress(by an osmoticum)have also been applied and shown effective to enhance the production of tanshinones in tiorrhiza hairy root cultures(Chen et al.2001;Zhang et al.2004;Shi et al.2007).To the best of our knowledge,only a few studies have been documented on the effects of elicitors,YE,SA,and MJ,on the secondary metabolite production in Agro-bacterium tumefaciens transformed tiorrhiza cell cultures from one research group(Chen and Chen1999, 2000)but not any study in normal cell cultures.The present study focuses on the effects of common biotic and abiotic elicitors including polysaccharides,heavy metal ions, SA and MJ,and osmotic stress(with sorbitol)on the growth and accumulation of three major tanshinones T-I, T-IIA,and CT in suspension culture of normal tior-rhiza cells.In addition to the effects of various elicitors on the total tanshinone content of cells,the study will examine the effects on different tanshinone species and the potential relationship to plant stress response.Material and methodsCallus induction and cell suspension cultureYoung stem explants of tiorrhiza Bunge were collected from the botanical garden at the Institute of Medicinal Plant Development,Chinese Academy of Med-ical Sciences,Beijing,China,in May2005.The fresh explants were washed with tap water,surface-sterilized with 75%ethanol for1min,and then soaked in0.1%mercuric chloride for10min and rinsed thoroughly with sterilized water.The clean and sterilized explants were cut into∼0.5-cm segments and placed on solid MS medium(Murashige and Skoog1962)supplemented with sucrose(30g l-1),2,4-D(2mg l-1)and6-BA(2mg l-1)to induce callus formation. The callus culture of tiorrhiza was maintained on a solid,hormone-free MS medium with8g l-1agar and 30g l-1sucrose at25°C in the dark and subcultured every 4weeks.The culture was deposited in Lab Y1210at The Hong Kong Polytechnic University with a collection number of Danshen cell-1.All experiments in this study were performed in suspension culture of tiorrhiza cells in a liquid medium of the same composition as for the solid culture but excluding agar.The cell suspension culture was maintained in shake-flasks,i.e.,125-ml Erlenmeyer flasks on an orbital shaker operated at110–120rpm,at 25°C in the dark.Each of the flasks was filled with25ml medium and inoculated with0.3g fresh cells from18–21-day-old shake–flask culture.Elicitor preparation and administrationEight elicitors were tested,each at three concentrations,in the initial elicitation experiments(Table1).These are representative of the four major classes of elicitors for the induction of plant responses and the stimulation of secondary metabolite production in plant tissue cultures (Zhou and Wu2006;Smetanska2008).All elicitors except MJ were prepared as a concentrated stock solution in water and autoclaved at121°C for15min,and stored at4°C in a refrigerator prior to use.Yeast elicitor(YE)was the polysaccharide fraction of yeast extract(Y4250,Sigma, St.Louis,MO,USA)prepared by ethanol precipitation as described previously(Hahn and Albersheim1978;Ge and Wu2005).In brief,yeast extract was dissolved in distilled water(20g/100ml)and then mixed with400ml of ethanol and allowed to precipitate for4days at4°C in arefrigerator.The precipitate was redissolved in100ml of distilled water and subjected to another round of ethanol precipitation.The final gummy precipitate was dissolved in 50ml of distilled water and stored at4°C before use.The concentration of YE was represented by total carbohydrate content which was determined by the Anthrone test using sucrose as a reference.Chitosan solution was prepared by dissolving0.5g crab shell chitosan(C3646,Sigma)in1ml glacial acetic acid at55–60°C for15min,and then the final volume was adjusted to50ml with distilled water and the pH adjusted to5.8with NaOH(Prakash and Srivastava 2008).MJ(Cat.39,270-7,Sigma-Aldrich)was dissolved in 95%ethanol and sterilized by filtering through a microfilter (0.2µm).SA(10,591-0,Sigma-Aldrich),sorbitol(S3755, Sigma),and the salts of heavy metals including cobalt chloride(C8661,Sigma-Aldrich),silver nitrate(S7276, Sigma-Aldrich),and cadmium chloride(C5081,Sigma-Aldrich)were dissolved in distilled water to the desired concentrations and adjusted to pH5.8.Elicitor treatment was administered to the shake–flask culture of tiorrhiza cell on day18,which was about 2–3days before reaching the stationary phase.This time point is usually favorable for elicitation when the biomass concentration is high(compared with earlier days of growth),and the cell metabolism is still active(compared with that during or after stationary phase;Buitelaar et al. 1992;Cheng et al.2006).Each of the elicitor solutions was added into the culture medium with a micropipette at the desired concentration.After the elicitor addition,the shake–flask culture of cells was maintained for another7days and then harvested for analysis.All treatments were performed in triplicate,and the results were averaged.After the initial experiments on the eight elicitors,the three most effective ones,Ag(25µM),Cd(25µM),and YE(100mg l-1)were applied in the following experiments on the time courses of elicitor-treated cell growth and tanshinone accumulation in the tiorrhiza cell culture.Measurement of cell weight,sucrose concentration, medium pH,and conductivityThe cells were separated from the liquid medium by filtration.The cell mass on the filter paper was rinsed thoroughly with water and filtered again,and blotted dry by paper towels and then dried at50°C in an oven to attain the dry weight.Sucrose concentration in the liquid medium was determined by the Anthrone test using sucrose as a reference(Ebell1969),and the medium pH and conduc-tivity were measured with the respective electrodes on an Orion720A+pH meter(Thermo Fisher Scientific,Inc., Beverly,MA,USA)and a CD-4303conductivity meter (Lutron,Taiwan),respectively.Measurement of PAL activityPhenylalanine ammonia lyase(PAL)was extracted from fresh tiorrhiza cells with borate buffer(pH8.8).The cells were ground in the buffer(0.15g ml-1)for2min with a pestle and mortar on ice,and then centrifuged at10,000rpm and4°C for20min to obtain a solid-free extract.The PAL activity was determined based on the conversion of L-phenylalanine to cinnamic acid as described by Wu and Lin(2002).Analysis of tanshinone contentsThe cell mass from culture was dried and ground into powder and extracted with methanol/dichloromethane(4:1, v/v,10mg ml-1)under sonication for60min.After removal of the solid,the liquid extract was evaporated to dryness and redissolved in methanol/dichloromethane(9:1,v/v). Tanshinone content was determined by high performance liquid chromatography(HPLC)on a HP1100system using C18column,acetonitrile/water(55:45,v/v)as the mobile phase,and UV detection at275nm as described previously (Shi et al.2007).Three tanshinone species CT,T-I,and T-IIA were detected and quantified with authentic standards obtained from the Institute for Identification of Pharmaceu-tical and Biological Products(Beijing,China).Total tanshinone content is the total content of the three tanshinones in the cells.Tanshinone content in the culture medium was negligible and not determined.ResultsCell growth and tanshinone accumulation in tiorrhiza cell cultureThe time course of tiorrhiza cell growth exhibited a lag phase or slow growth period in the first3–6days, a rapid,linear growth period between day9–18,and aTable1Elicitors and concentrations tested in the initial experiments Elicitors Unit ConcentrationC1C2C3Cobalt chloride(Co)µM 5.02550 Silver nitrate(Ag)µM 5.02550 Cadmium chloride(Cd)µM 5.02550 Salicylic acid(SA)µM1050100 Methyl jasmonate(MJ)µM1050100 Yeast elicitor(YE)mg l-150100200 Chitosan(CH)mg l-150100200 Sorbitol(SO)g l-152550stationary or declining phase in the later days,reaching the maximum biomass concentration (8.1g l -1)around day 21.The total tanshinone content of cells remained at a very low level from days 1–12and then increased steadily from days 12–27to a maximum of 0.16mg g -1.A significant portion (65%)of the tanshinone accumulation or content increase occurred during the stationary phase from days 21–27(Fig.1a ),which is characteristic of secondary metabolite production in a batch culture process.The time course of sugar (sucrose)concentration (Fig.1b )was nearly sym-metrical to that of cell growth,indicating a direct correlation of the cell growth (or biomass production)to sugar consumption.As the major carbon source,sugar was required for the S .miltiorrhiza cell growth,and when it was depleted (around day 21),the cell growth stopped,and the biomass concentration began to drop.As seen from Fig.1b ,the medium pH showed a notable drop in the first 3days (due to consumption of NH 4+and release of protons)and a gradual increase after day 6(due to consumption of nitrate NO 3-)(Morard et al.1998).Effects of various elicitors on cell growth and tanshinone productionFigure 2shows the effects of elicitor treatments on the cell growth and tanshinone accumulation in S .miltiorrhiza cell cultures,which were dependent both on the elicitor species and elicitor dose.As seen from Fig.2a ,most of the elicitor treatments except Co 2+and sorbitol at lower concentrations suppressed the cell growth to a lower biomass concentra-tion than that of the untreated control culture,and the growth suppression was more severe at a high elicitor dose.On the other hand,most of the elicitor treatments except Co 2+,sorbitol,SA,and MJ at lower concentrations increased the total tanshinone content of cell to a higher level than in the control (Fig.2b ).Overall the results indicated that the enhancement of tanshinone accumulation by an elicitor treatment concurred with a notable suppres-sion of cell growth or biomass production.Nevertheless,some of the elicitors had a much stronger stimulating effect on the tanshinone accumulation than the suppressing effect on the cell growth.In particular,Ag and Cd both at 25μM,and YE at 100mg l -1increased the total tanshinone content to 2.30mg g -1,about 11.5-fold versus that of the control (0.20mg g -1),but decreased the biomass production by no more than 50%(5.1–5.5g l -1versus 8.9g l -1).Another three elicitors,SA,MJ (both at 50μM),and sorbitol (50g l -1)increased the total tanshinone content by 2–3-fold but decreased the biomass by 30–45%compared with the control.The stimulating effect of chitosan on tanshinone accumulation (about 6-fold)was stronger than SA,MJ,and sorbitol but much weaker than Ag,Cd,and YE,while its suppressing effect on the cell growth was as severe as Ag,Cd,and YE.In summary,the results indicate that Ag,Cd,YE are the most favorable elicitors for the tanshinone production in S .miltiorrhiza cell culture and were used in the following experiments.Figure 3shows the time courses of cell growth and tanshinone production after treatment with the three most effective elicitors Ag (25μM),Cd (25μM),and YE (100mg l -1)and the control culture.All three elicitor treatments caused a steady decline of biomass concentration from initially 8.5g l -1to 5.3g l -1on day 6while biomass in00.040.080.120.160.20246810TT content (mg g -1)C e l l b i o m a s s (g d w l -1)dw TTa4.85.1 5.45.76.001020304036912151821242730p HS u c r o s e (g l -1)Culture time (d)bSucrosepHFig.1Time courses of biomass and total tanshinone content (a ),residue sugar (sucrose)and medium pH (b )in S .miltiorrhiza cell cultures (error bars for standard deviations,n =3)246810C e l l b i o m a s s (g l -1)0.00.51.01.52.02.5Control AgCdSAMJYECH SOT T c o n t e n t (m g g -1)Elicitor treatmentCo Fig.2Effects of various elicitors on biomass growth (a )andtanshinone production (b )in S .miltiorrhiza cell cultures (elicitors added to cultures on day 18at three concentrations C1,C2,and C3as shown in Table 1,and cultures harvested on day 25;error bars for standard deviations,n =3)the control culture was increased during this period (Fig.3a ).In the meantime,the tanshinone content of cells in the three elicitor-treated cultures increased sharply and most rapidly by Ag (from 0.14to 1.98mg g -1),while that of control increased slightly (from 0.14to 0.21mg g -1;Fig.3b ).The volumetric total tanshinone yields (the products of total tanshinone content and cell dry weight)were 1.9mg l -1in the control,and 9.2mg l -1,10.7mg l -1and 11.7mg l -1in cultures treated with 100mg l -1YE,25μM Cd,and Ag,respectively (on day 6).Another test was performed on the effects of two and three elicitors in combinations in the S .miltiorrhiza cell culture.As shown in Fig.4,the tanshinone content was increased about 20%with either two elicitors and about 40%with all three elicitors in combination compared with that with a single elicitor.The results suggest an additive or synergistic effect of these elicitors on the tanshinone accumulation in the cells.However,the combined use of two or three elicitors also suppressed the cell growth (biomass)more severely than with a single elicitor.Effects of elicitor treatments on different tanshinone species Of the three tanshinone species detected,CT was stimulated most significantly by all elicitors without exception;T-IIA was stimulated by most elicitors,and T-I was stimulated significantly only by chitosan but slightly stimulated or suppressed by other elicitors (Table 2).The highest CT content was about 2mg g -1(1,854–2,011μg g -1)in cellcultures treated with 25μM Ag and Cd,and 100mg l -1YE,about 31–34fold of the control level (60μg g -1),the highest T-I content 0.27mg g -1with 100mg l -1chitosan (3.4-fold of the control 80μg g -1)and the highest T-IIA content 0.37mg g -1with 25μM Cd (6-fold of the control 60μg g -1).As seen from the HPLC chromatograms (Fig.5),the cultures treated with the three different elicitors exhibited a similar profile with virtually identical major peaks.The experimental results do not suggest any specificity of particular tanshinone species to the type of elicitors,YE and chitosan as biotic polysaccharides,Cd and Ag as abiotic heavy metals,or SA and MJ as plant stress signaling pared with that of control,the HPLC profiles of elicitor-treated cultures also had three new unknown peaks appearing before the CT peak,between 10.0–11.5min and a high peak at 11.1min,which0.00.51.01.52.02.5123456T T c o n t e n t (m g g -1)Time after treatment (d)b4681012C e l l b i o m a s s (g l -1)Control Ag 25Cd 25YE 100aFig.3Time courses of biomass (a )and total tanshinone content (b )in S .miltiorrhiza cell cultures after treatment with Ag (25µM),Cd (25µM),and YE (100mg l -1;error bars for standard deviations,n =3)24681012345Cell dry weight (g l -1)T T c o n t e n t (m g g -1)Elicitor treatmentTTdwFig.4Effects of single and combined elicitors on S .miltiorrhiza cell growth and tanshinone accumulation (elicitors added to cell cultures on day 18at the same concentrations as in Fig.3,and cultures harvested on day 25;error bars for standard deviations,n =3)Table 2Effects of various elicitors on the accumulation of three tanshinones in S .miltiorrhiza cells Treatment aContent,μg/g (fold of content control)CTT-IT-IIA Control 59.9(1)81.6(1)57.6(1)Co-50263.7(4.4)67.5(0.83)55.5(0.96)Ag-251,817.5(30)71.0(0.87)225.8(3.9)Cd-251,854.0(31)80.3(0.98)369.0(6.4)SA-100390.0(6.5)78.5(0.96)72.8(1.3)MJ-100299.8(5.0)109.5(1.3)82.6(1.4)YE-1002,011.4(34)90.3(1.1)190.3(3.3)CH-100597.2(10)276.0(3.4)98.8(1.7)SO-50584.6(9.8)56.9(0.70)83.0(1.4)CT cryptotanshinone,T-I tanshinone I,T-IIA tanshinone-IIAaNumber after each elicitor symbol represents the elicitor concentra-tion as shown in Table 1may be ascribed to tanshinone relatives of higher polarity than CT induced by the elicitors.PAL activity,pH,and conductivity changes induced by elicitorsFigure 6shows the changes of intracellular PAL activity and medium pH and conductivity in the S .miltiorrhiza cell culture after the treatment by Ag (25μM),Cd (25μM),and YE (100mg l -1).The PAL activity of cells was stimulated by all three elicitors to the similar level,from 1.4-to 1.9-fold of the control level over 6days (Fig.6a ).PAL is a key enzyme at the entrance step in the phenylpropanoid pathway in plants,and its activity increase stimulated by the elicitors is suggestive of an enhanced secondary metabolism in the plant cells (Taiz and Zeiger 2006).The pH and conductivity of culture medium were also increased (to higher levels than those of the control)by all three elicitors but more significantly by YE (Fig.6b,c ).Most significant increases (differences from the control level)in the medium pH and conductivity were shown in the very early period from day 0–1.The increase in medium conductivity in the early period was most probably attributed to the release of potassium K +ion from the cells or K +efflux across the cell membrane (Zhang et al.2004).Transient medium pH increase (alkalinization)and K +efflux across the cell membrane are early and important events in the elicitation of plant responses and phytoalexin production (Ebel and Mithöer 1994;Roos et al.1998).The conductivity decline in the later period after day 1of Ag +and Cd 2+-treated cultures and the control cultures can be attributed to the consumption of inorganic and mineral nutrients in the culture medium (Kinooka et al.1991).Overall,the results here provide further evidence forthe01234R e l a t i v e P A L a c t i v i t yControl Ag CdYEa5.05.45.86.26.6M e d i u m p H b2.03.04.05.06.00246M e d i u m c o n d u c t i v i t y (m S )Time after treatment (d)cFig.6Time courses of PAL activity (a ),medium pH (b ),and conductivity (c )of S .miltiorrhiza cell cultures after elicitor treatments in comparison with the control (error bars for standard deviation,n =3)elicitor activities of Ag,Cd,and YE in stimulating the stress responses and secondary metabolism of the S. miltiorrhiza cells.DiscussionThe effects of various elicitors on tanshinone accumulation found here in the normal tiorrhiza cell cultures are in general agreement with those found in transformed cell and hairy root cultures of tiorrhiza.In transformed cell cultures(Chen and Chen1999),the CT accumulation was also stimulated significantly by YE but not by SA or MJ alone,and YE also inhibited the cell growth.The tanshinone(mainly CT)production in hairy root cultures was also enhanced significantly(3–4fold)by Ag(Zhang et al.2004)and YE(Shi et al.2007).In all these culture systems,CT was the major tanshinone species stimulated by various elicitor treatments.CT has been identified as a phytoalexin in tiorrhiza plant which plays a defense role against pathogen invasion of the plant(Chen and Chen 2000).In this connection,the stimulated CT accumulation by the elicitors may be a defense or stress response of the cells.CT was also the major diterpenoid produced by a normal tiorrhiza cell line which was initially grown in the MS medium and then transferred to a production medium containing only about half of the nutrient compo-nents of the MS medium(Miyasaka et al.1987).It is very possible that the improvement of CT yield in this production medium was also attributed,at least partially, to the stress imposed by the nutrient deficiency which suppressed growth but stimulated secondary metabolite accumulation.MJ or its relative jasmonic acid has been shown effective for stimulating a variety of secondary metab-olites in plant tissue cultures such as hypericin in Hypericum perforatum L.(St.John’s Wort)cell cultures (Walker et al.2002),paclitaxol(diterpenoid)and related taxanes in various Taxus spp.and ginsenosides in Panax spp.(Zhong and Yue2005),and bilobalide and ginkgo-lides in Ginkgo biloba cell cultures(Kang et al.2006). However,MJ showed only a moderate or insignificant stimulating effect on tanshinone accumulation in normal and transformed tiorrhiza cell cultures.The discrep-ancy suggests that the effects of various elicitors on secondary metabolite production in plant tissue cultures are dependent on the specific secondary metabolites.This argument is also supported by the much stronger stimu-lation of CT than T-I and T-IIA by most elicitors found in our tiorrhiza cell cultures.In addition,the hairy roots appeared more tolerant to the elicitor stress,and the growth was less inhibited by the elicitors or even enhanced in some cases,e.g.,by YE(Chen et al.2001)and sorbitol(Shi et al.2007).Moreover,sorbitol as an osmotic agent significantly stimulated the tanshinone accumulation(3–4folds)in tiorrhiza hairy root cultures,but not so significantly in the cell cultures.This shows that the elicitor activities for the same metabolites can vary with the tissue culture systems.In conclusion,the polysaccharide fraction of yeast extract and two heavy metal ions Ag+and Cd2+were potent elicitors for stimulating the tanshinone production in tiorrhiza cell culture.The stimulated tanshinone production by most elicitors was associated with notable growth suppression.CT was more responsive to the elicitors and enhanced more dramatically than another two tanshinones,T-I and IIA.The results from this study in the tiorrhiza cell cultures and from previous studies in hairy root cultures suggest that the cell and hairy root cultures may be effective systems for CT production, provided with the elicitors.As most of the elicitor chemicals are commercially available or can be readily prepared in the laboratory and easily administered to the cell and root cultures,they are suitable for practical applications in the laboratory or large-scale production. Acknowledgements This work was supported by grants from The Hong Kong Polytechnic University(G-U502and1-BB80)and the China Hi-Tech Research and Development Program(2006AA10A209).ReferencesBuitelaar RM,Cesário MT,Tramper J(1992)Elicitation of thiophene production by hairy roots of Tagetes patula.Enzyme Microb Technol14:2–7Chen H,Chen F(1999)Effects of methyl jasmonate and salicylic acid on cell growth and cryptotanshinone formation in Ti transformed Salvia miltiorrhiza cell suspension cultures.Biotechnol Lett 21:803–807Chen H,Chen F(2000)Effect of yeast elicitor on the secondary metabolism of Ti-transformed Salvia miltiorrhiza cell suspension cultures.Plant Cell Rep19:710–717Chen H,Chen F,Chiu FCK,Lo CMY(2001)The effect of yeast elicitor on the growth and secondary metabolism of hairy root cultures of Salvia miltiorrhiza.Enzyme Microb Technol28:100–105Cheng XY,Zhou HY,Cui X,Ni W,Liu CZ(2006)Improvement of phenylethanoid glycosides biosynthesis in Cistanche deserticola cell suspension cultures by chitosan elicitor.J Biotechnol 121:253–260Chong TM,Abdullah MA,Lai QM,Nor’Aini FM,Lajis NH(2005) Effective elicitation factors in Morinda elliptica cell suspension culture.Process Biochem40:3397–3405Ebel J,Mithöer A(1994)Early events in the elicitation of plant defence.Planta206:335–348Ebell LF(1969)Variation in total soluble sugars of conifer tissues with method of analysis.Phytochemistry8:227–233Ge XC,Wu JY(2005)Tanshinone production and isoprenoid pathways in Salvia miltiorrhiza hairy roots induced by Ag+and yeast elicitor.Plant Sci168:487–491。

1-s2.0-S0263436814001590-main

Effect of rare earth elements on the consolidation behavior and microstructure of tungsten alloysMingyue Zhao a ,Zhangjian Zhou a ,⁎,Qingming Ding a ,Ming Zhong a ,Kameel Arshad ba School of Materials Science and Engineering,University of Science and Technology Beijing,Beijing 100083,China bSchool of Physics and Nuclear Energy Engineering,Beihang University,Beijing 100191,Chinaa b s t r a c ta r t i c l e i n f o Article history:Received 11February 2014Available online 23July 2014Keywords:Rare earth element Tungsten alloyConsolidation behavior MicrostructureThe effects of rare earth elements (Y 2O 3,Y and La)on the consolidation behavior,microstructure and mechanical properties of tungsten alloys were investigated in this work.The starting powders were mechanical alloyed (MA)and then consolidated by spark plasma sintering (SPS).It was found that Y doping was bene ﬁcial to obtain fully dense tungsten alloys with more re ﬁned grains as compared to any other rare earth elements.The maximum values of Vickers microhardness and bending strength obtained from W –0.5wt.%Y alloy reached up to 614.4HV 0.2and 701.0MPa,respectively.©2014Elsevier Ltd.All rights reserved.IntroductionTungsten is a promising candidate material for high temperature applications due to its attractive properties,such as high melting point,high conductivity,low thermal expansion coef ﬁcients and low sputtering yield [1].However,a major limitation of its use is the inherently high ductile –brittle transition temperature (DBTT)and low recrystallization temperature.Fine grained tungsten materials have shown improved properties in terms of reduced brittleness and improved toughness and strength [1,2].However,the improved mechanical properties will be deteriorated when exposed to high temperatures for long time and when the service temperature is higher than the recrystallization temperature of pure tungsten.Recent studies suggested that the dispersion of high temperature oxide nanoparticles,such as La 2O 3and Y 2O 3,will not only inhibit the grain growth of W during the consolidation but also stabilize the microstructure when exposed to higher temperature [3,4].It is well known that,the impurities,especially for oxygen,have det-rimental in ﬂuence on the sinterability of tungsten powders and make tungsten materials embrittlement.Thus adding rare earth elements in the metallic state instead of the oxidic state should be better for fabrica-tion of high performance tungsten alloys,due to the high af ﬁnity of rare earth elements with oxygen.A recent research conducted by L.Veleva et al.[5]found that the relative density of W –(0.3–2)wt.%Y appeared higher than that of W –(0.3–2)wt.%Y 2O 3,however,the microhardnessappeared always lower than that of W –(0.3–2)wt.%Y 2O 3.From the viewpoint of oxygen absorption,it is suggested that La will be better than Y when used as alloying element for fabrication of W [6].However there are almost no reports on W –La alloy and their comparison with W –Y alloy.It will be interesting and important to investigate the effects of different rare earth elements on the densi ﬁcation of W and their mechanical properties.This is the motivation of this work.In this study the effect of rare earth elements,including Y 2O 3,Y and La on the consolidation behavior of W under the same sintering condi-tion was investigated.The microstructural evolution and mechanical properties of different rare earth tungsten materials were examined and compared.Experimental proceduresPowders of commercial pure W (with an average particle size of 2.0μm and a purity of 99.9%),rare earth element of Y or La (with an av-erage particle size of 48μm and a purity of 99.9%),and rare earth oxide of Y 2O 3(with an average particle size of 30nm and a purity of 99.9%)were used as starting materials.The mixture powders of W –0.5wt.%Y 2O 3(named as WYO),W –0.5wt.%Y (named as WY)or W –0.5wt.%La (named as WL)were mechanical alloyed (MA)in a planetary ball mill,respectively.The MA parameters can be found in our previous work [7,8].Then,the MA treated powders were placed into graphite tool in glove box and sintered by spark plasma sintering (SPS)in vacuum.Fig.1shows the temperature and pressure pro ﬁle of SPS as a function of time.In order to get fully dense bulk materials by suppress-ing the pore-boundary separation,the samples were ﬁrst sintered at 1373K for 2min and then sintered at 1873K according to [9].Int.Journal of Refractory Metals and Hard Materials 48(2015)19–23⁎Corresponding author at:Laboratory of Special Ceramics and Powder Metallurgy,School of Materials Science and Engineering,University of Science &Technology Beijing,Beijing 100083,PR China.Tel./fax:+861062334951.E-mail address:zhouzhj@ (Z.Zhou)./10.1016/j.ijrmhm.2014.07.0140263-4368/©2014Elsevier Ltd.All rightsreserved.Contents lists available at ScienceDirectInt.Journal of Refractory Metals and Hard Materialsj o u r n a l h o m e p a g e :w w w.e l s e v i e r.c o m/l o c a t e /I J R M H MThe shrinkage of the specimens was continuously monitored by the displacement of the punch rod.The density of the compacts was measured by Archimedes method.A ﬁeld emission scanning electron microscope (FE-SEM)equipped with Energy-dispersive X-ray Spectros-copy (EDS)and Scanning electron microscope (SEM)were employed to investigate the microstructural features,i.e.,the element distribution,and the size and morphology of the grains and the pores of the samples.Moreover,XRD was used to determine the phase and X-ray diffraction analysis was made by the Rietveld method using the Full prof program [10].The average crystallite size as well as the internal stress of the MA treated powders were determined from the diffraction peak widths taking into account the diffractometer resolution function.Vickers mi-crohardness was measured at room temperature by applying a load of 1.96N for 15s.Three point bending tests were conducted on specimens with dimensions of 2mm ×3mm ×18mm with a span of 13.1mm and a crosshead speed of 0.5mm/min.The thermal behavior of the MA treated powders in the range 373–1723K was investigated by differen-tial scanning calorimetry (DSC)at a heating rate of 10K/min in ﬂowing pure Ar.Results and discussion Consolidation behaviorFig.2compares the consolidation behavior of all tungsten alloys as a function of temperature.It can be clearly seen that the displacement of WY alloy is similar with that of WL alloy,and shows quite different ten-dency from that of WYO alloy,especially at the sintering temperature of 1373K.For WY and WL alloys,the displacement decreased by 0.6mm between 993K and 1373K due to the thermal expansion of graphite punch rods and the matrix overweighing the contribution of pre-compaction,and continued to decrease at the sintering temperature of 1373K.For WYO alloy,the displacement experiences a slower down-ward trend between 993K and 1373K and a weak upward trend at 1373K.After that,the displacement of WY sees a similar trend with that of WYO.It was found that the WY alloy experienced a substantial decrease in the displacement while the WYO alloy experienced a slight increase at the temperature of 1373K.This result is likely to arise from the formation of a higher volume of Y 2O 3due to the oxidation of Y ele-ment in the WY system.Chemical analysis of the consolidated compacts was performed by the HORIBA EMIA-820V and LECO TCH600devices to measure the C and O contents,respectively.It shows that the C contents were about 240ppm for various tungsten materials fabricated under the same conditions.The amount of oxygen content which existed in MA treated WY powders was 0.4808wt.%,which is enough for the reactionwith added Y particles to form Y 2O 3.Fig.3shows the DSC curve of the MA treated WY powders in the range 373–1723K.A weak exothermic peak at 1500K with an onset temperature of 1400K is found.It probably corresponds to the oxidation of the metallic Y with the residual oxygen in a hermetically sealed pan,which also illustrates that the remaining Y particles are likely to start to react with oxygen around 1373K during SPS.Moreover,a sharp strong and a small exothermic peak can be clear-ly seen at 1003K and 1173K,respectively.According to [11,12],these peaks indicate that the strain relief took place during the heating of MA treated powders.Similar results on the oxygen analysis and the thermal behavior are also found for MA treated WL powders.Fig.4shows the milling and sintering effect on the XRD patterns of the investigated samples.It is obvious that the diffraction peaks are broadened after milling,which was caused by the re ﬁnement of powder particles and a high level of internal strain in the W grains fabricated by the MA process.After sintering,the diffraction peaks become narrow again due to the grain growth and strain relief.The quantitative data on such grain growth and strain relief can be obtained by the compari-son of lattice parameters after each stage of the powder processing (Table 1).It should be noted that the XRD patterns for all samples after milling exhibit a single BCC phase,suggesting that the rare earth elements were dissolved into the W lattice.This solid solutionduringFig.1.The temperature and pressure pro ﬁle as a function of time for the sintering experiments of rare earth tungstenalloys.Fig.2.The real time sintering curves of all samples without removing the contribution of the thermal expansion of the graphite tool andmatrix.Fig.3.DSC curve of the MA treated WY powder.The peak temperatures of thermally induced transformation of the powders are indicated by arrows.20M.Zhao et al./Int.Journal of Refractory Metals and Hard Materials 48(2015)19–23the MA process can be further demonstrated by the lattice parameter increase of the MA treated powders compared with that of the starting pure tungsten powder (Table 1).Microstructure observationMicrostructure of the fracture surfacesThe fracture surfaces of WY,WYO and WL samples are presented in Fig.5.It can be clearly seen that the rare earth elements in ﬂuence the grain re ﬁnement signi ﬁcantly.Fig.6shows the grain size distribution which was determined from the SEM micrographs of fracture surfaces.For each image,about 130grains were chosen randomly to eliminate the bias of grain counting.The grain size distributions of WL and WYO alloys are in the range from 1.6to 8.0μm and from 0.8to 4.4μm,respec-tively,and their average grain sizes are 2.46μm and 4.62μm,respective-ly;while,the average grain size of WY alloy is only 1.10μm,which is much smaller than that of WL and WYO alloys.The grain size distribu-tion of WY alloy is in the range from 0.3to 2.0μm,which is much nar-row as compared with that of WL and WYO alloys.Moreover,it is worth noting that the average grain size acquired from the SEM images of fracture surfaces has a remarkable consistency with those calculated by the Rietveld method using the Full prof program,as shown in Table 1.More careful analysis of Fig.6reveals that the WY alloy is denser than WYO and WL alloys.Many big worm-like pores (indicated by yel-low arrows)and small pores (indicated by white dot circles)can be found for WYO and WL alloys on the surface of individual tungstengrains and in the triple junctions.It is easy to learn that the tungsten grains with different additions grew up in a different speed (WL N WYO N WY)according to the average grain size of each stage of powder processing.Besides,the grain growth of pure tungsten or ODS W-based materials sintered by SPS starts between 1373K and 1773K according to literature [9,13].Under a certain pressure between 1773K and 1873K in our present work,the smaller the grain size,the easier the re-arrangement and plastic deformation,and thus higher shrinkage can be achieved.During the holding time at sintering temperature (1873K),grain growth took place simultaneously with further densi ﬁcation,which was achieved dominantly by more homogeneous interfacial atomic diffusion but with minimized involvement of surface diffusion according to [9].Meanwhile,the worm-like pores could be formed if the holding time at sintering temperature of 1873K was not enough for W –0.5La alloy having a large grain size.The microstructure of chemically etched surfacesThe microstructures of chemically etched surface are illustrated in Fig.7.EDS analysis indicated that the black phases which existed in WYO,WY and WL alloys are rare earth oxides (indicated by blue ar-rows)and the dark gray phases are pores (indicated by red arrows).For WY alloy (Fig.7b),pores can hardly be found,which is consistent with the microstructure observation of the fracture surface.Besides,ﬁne Y 2O 3particles are distributed uniformly along grain boundaries of WY alloy;while for WYO and WL alloys (Fig.7a and c),many micro-scale pores are found in triple junctions and tungsten grain boundaries,especially for WL alloy.Moreover,the FESEM images shown in Fig.7a and c reveal that the oxide particles are irregular and not distributed uniformly.In the XRD measurements performed on the WL alloy (Fig.4and Table 1),a weak diffraction peak of La 2O 3phase and lattice parameter decrease of sintered WL alloy are observed,which also suggest that the La particles separate from tungsten grains and become micro-scale La 2O 3during sintering.The densi ﬁcation analysisTable 2shows the relative density of the rare earth tungsten alloys.The relative density of WY reaches 99.4%,which is much higherthanFig.4.Effect of milling and SPS sintering on the XRD patterns of rare earth tungsten alloys.(a)MA treated powders,and (b)sintered compacts.Table 1Lattice parameters after each stage of the powder processing and the average grain size ac-quired from the SEM images of fracture surfaces.SamplePowder Sintered compact Crystallite size (nm)lattice strain (%)a (W:nm)Grain size (nm)Lattice strain (%)Grain size (nm)—SEM WY 8050.3510.31646215220.0701100WL 4100.3010.31659956650.0414620WYO 6200.3860.31653424820.0342460W11740.0450.31604021M.Zhao et al./Int.Journal of Refractory Metals and Hard Materials 48(2015)19–23the WYO (92.1%)and WL (88.3%).This result is agreeable with the mi-crostructure observation.Owing to the grain boundary cleaning effect and sintering enhancing effect of Y particles during SPS,Y doping is ben-e ﬁcial to achieve fully dense tungsten alloys than Y 2O 3doping.On the other hand,the well-distributed ﬁne Y 2O 3dispersions which existed in WY alloy play a prominent role in the re ﬁnement of tungsten grains,thus dense ﬁne grained sample can be obtained under the present sintering process.Kim et al.[14]reported that the second phases can act as obstacles in inhibiting the grain growth only in solid phase sintering.Owing to the formation of metallic La liquid phase at 1193Kaccording to the phase diagram Mo –La and then the formation of micro-scale and non-uniformly distributed La 2O 3dispersions as a result of oxidation,the grain growth speed of WL alloy is much higher than that of WYO and WY alloys.Thereby,the relative density of WL alloy is lower than that of WYO alloy and WY alloy even though La particles can exert cleaning effect on the tungsten grain boundaries.Besides,in accordance with literatures [4,15,16],the internal energy originating from the signi ﬁcant strain of the particles could serve as a part of sintering driving force.As shown in Table 1,the lattice strain of WL alloy is 0.301%,lower than that of WYO (0.386%)and WY (0.351%),which is another reason for the lower relative density of WL alloy.The basic mechanical propertiesVickers microhardness and bending strength of the rare earth tung-sten alloys were also listed in Table 2.Of all the three kinds of tungsten materials,the hardness of WY sample is 614.4HV 0.2,much higher than that of WYO (445.2HV 0.2)and WL (303HV 0.2).The lower hardness of WYO and WL alloys originates from the lower relative density and coarse grain size,as shown in Figs.5and 6.Moreover,WY exhibits the highest bending strength (701MPa)among these tungsten alloys,which is 11%and 88%higher than that of WYO and WL alloys.As shown in Fig.5,the remaining pores,including worm-like pores and small pores,reduce the contact area of tungsten grains,thus the bending strength of WYO and WL to some extent decreases.Besides,the coarse grain size (Fig.6)and inhomogeneous dispersions of oxide particles (Fig.7)of WYO and WL alloys are also the reason for their low bending strength.ConclusionsTungsten alloys were successfully fabricated by adding different rare earth elements to W matrix.The effect of dispersing rare earthelementsFig.5.SEM micrographs of fracture surfaces for:(a)WYO,(b)WY,and (c)WL;the yellow arrows denote worm-like pores existed on the surface of individual grains,and the white dot circles denote pores located in the triplejunctions.Fig.6.Histograms of the grain size distributions for WYO,WY and WL alloys.22M.Zhao et al./Int.Journal of Refractory Metals and Hard Materials 48(2015)19–23on the microstructure evolution and mechanical properties of the tung-sten alloys can be concluded as follows:(1).The relative density of WY,WYO and WL alloy reached 99.4%,92.1%and 88.3%,respectively.The Y doping was bene ﬁcial toobtain fully dense tungsten alloys as compared with Y 2O 3doping and La doping because the ﬁnely distributed second phase parti-cles suppressed the tungsten grain growth and thus ensured the suf ﬁcient grain boundary volume available for densi ﬁcation by grain boundary diffusion.The analysis of consolidation behavior and thermal behavior of MA treated WY or WL powders revealed that the added Y or La particles were likely to start to react with oxygen around 1373K during SPS.(2).The average grain sizes of WY,WYO and WL alloys were 1.10μm,2.46μm and 4.62μm,respectively.The Y doping was bene ﬁcial to obtain tungsten alloys with more re ﬁned tungsten grains as com-pared with Y 2O 3doping and La doping.(3).Of all the three kinds of rare earth tungsten alloys,WY alloy ex-hibited the highest mechanical properties at room temperature.The maximum values of Vickers microhardness and bending strength reached up to 614.4HV 0.2and 701.0MPa,respectively.AcknowledgmentsThe authors would like to express their thanks for the ﬁnancial support of the National Natural Science Foundation of China under grant No.50634060.References[1]Zhang Y,Ganeev AV,Wang JT,Liu JQ,Alexandrov IV.Observations on the ductile-to-brittle transition in ultra ﬁne-grained tungsten of commercial purity.Mater Sci Eng A 2009;503:37–40.[2]Kitsunai Y,Kurishita H,Kayano H,Hiraoka Y,Igarashi T,Takida T.Microstructure andimpact properties of ultra-ﬁne grained tungsten alloys dispersed with TiC.J Nucl Mater 1999;271–272:423–8.[3]Kim Y,Lee KH,Kim E,Cheong D,Hong SH.Fabrication of high temperature oxidesdispersion strengthened tungsten composites by spark plasma sintering process.J Refract Met Hard Mater 2009;5:842–6.[4]Wang HT,Fang ZZ,Hwang KS,Zhang HB,Siddle D.Sinter-ability of nanocrystallinetungsten powder.Int J Refract Met Hard Mater 2010;28:312–6.[5]Veleva L,Oksiuta Z,Vogt U,Baluc N.Sintering and characterization of W –Y andW –Y 2O 3materials.Fusion Eng Des 2009;84:1920–4.[6]Brown PH,Rathjen AH,Graham RD,Tribe DE.Chapter 92rare earth elements inbiological systems.Handbook on the physics and chemistry of rare earths;1990.p.423–52.[7]Zhou ZJ,Tan J,Qu DD,Pintsuk G,Rödig M,Linke J.Basic characterization of oxidedispersion strengthened ﬁne-grained tungsten based materials fabricated by me-chanical alloying and spark plasma sintering.J Nucl Mater 2012;431:202–5.[8]Tan J,Zhou ZJ,Zhu XP,Guo SQ,Qu DD,Lei MK,et al.Evaluation of ultra-ﬁne grainedtungsten under transient high heat ﬂux by high-intensity pulsed ion beam.Trans Nonferrous Metals Soc China 2012;22:1081–5.[9]Ma J,Zhang JZ,Liu W,Shen ZJ.Suppressing pore-boundary separation during sparkplasma sintering of tungsten.J Nucl Mater 2013;438:199–203.[10]Rodríguez-Carvajal J.Recent advances in magnetic structure determination byneutron powder diffraction +FullProf.Physica B 1993;192:55–6.[11]Muñoz A,Monge MA,Savoini B,Rabanal ME,Garces G,Pareja 2O 3-reinforced Wand W –V alloys produced by hot isostatic pressing.J Nucl Mater 2011;417:508–11.[12]Maweja K,Phasha MJ,Choenyane LJ.Thermal stability and magnetic saturation ofannealed nickel –tungsten and tungsten milled powders.J Refract Met Hard Mater 2012;30:78–84.[13]Yar MA,Wahlberg S,Bergqvist H,Salem HG,Johnsson M,Muhammed M.Spark plas-ma sintering of tungsten –yttrium oxide composites from chemically synthesized nanopowders and microstructural characterization.J Nucl Mater 2011;412:227–32.[14]Kim Y,Hong MH,Lee SH,Kim EP,Lee S,Noh JW.The effect of yttrium oxide on thesintering behavior and hardness of tungsten.Met Mater Int 2006;12:245–8.[15]Han Y,Fan JL,Liu T,Cheng HC,Tian JM.The effects of ball-milling treatment on thedensi ﬁcation behavior of ultra-ﬁne tungsten powder.Int J Refract Met Hard Mater 2011;29:743–50.[16]Prabhu G,Chakraborty A,Sarma B.Microwave sintering of tungsten.Int J Refract MetHard Mater 2009;27:545–8.Fig.7.FESEM micrographs of chemically etched surface of:(a)WYO,(b)WY,and (c)WL.Table 2The relative density and basic mechanical properties of rare earth tungsten alloys.Sample Relative density (%)Microhardness (HV 0.2)Bending strength (MPa)WYO 92.1445.2631WY 99.4614.4701WL88.3303372.123M.Zhao et al./Int.Journal of Refractory Metals and Hard Materials 48(2015)19–23。

awards-list

Accademia Nazionale dei lincei International Feltrinelli Prize (ACD 12/09)Advances in Neuroblastoma Research (ANR) Best Paper Award on the presentation of "The MYCN Oncogene is a Direct Target of miR-34a" (ACD 12/08)Albany Medical Center Albany Medical Center Prize in Medicine and Biomedical Research (ACD 2/05)Albert & Mary Lasker Foundation Albert Lasker Medical Research Awards (ACD 2/05)Alcon Research Institute Alcon Research Institute Award (ACD 12/08) (NEAC 9/16/08)Alexander von Humboldt Foundation Humboldt Research Award (2/06) (See end note)American Academy of Child & Adolescent Psychiatry •Irving Philips Award for Prevention (ACD 12/10) (NEAC 9/14/10)American Academy of Dermatology •Awards for Young Investigators in Dermatology (ACD 2/05)•Marion B Sulzberger Memorial Award & Lectureship (ACD 3/05)•Lila Gruber Memorial Cancer Research Award (ACD 3/05) (NEAC 1/11/05)•Astellas Award (ACD 12/07) (NEAC 7/17/07)•Eugene Von Scott Award for Innovative Therapy (ACD 6/08)American Academy of Neurology •AAN Award for Creative Expression of Human Values in Medicine (ACD 3/05)•Alliance Awards: Founders (ACD 3/05)•Dreifuss-Penry Epilepsy Award (ACD 3/05)•Harold Wolff-John Graham Award (ACD 3/05)•John Dystel Prize for Multiple Sclerosis Research (ACD 3/05)•Medical Student Essay Award - Extended Neuroscience Award (ACD 3/05)•Medical Student Essay Award - G. Milton Shy Award (ACD 3/05)•Medical Student Essay Award - Roland P. Mackay Award (ACD 3/05)•Medical Student Essay Award - Saul R. Korey Award (ACD 3/05)•Michael S. Pessin Stroke Leadership Prize (ACD 3/05)•Movement Disorders Research Award (ACD 3/05)•Normal Geschwind Prize in Behavioral Neurology (ACD 3/05)•Potamkin Prize for Research in Pick's Alzheimer's and Related Diseases (ACD 3/05)•Preuss Award in Clinical Neuro-Oncology (ACD 3/05)•Research Award in Geriatric Neurology (ACD 3/05)•Sheila Essey Award - An Award for ALS Research (ACD 3/05)•Sleep Science Award (ACD 3/05)•S. Weir Mitchell Award (ACD 3/05)American Academy of Orthopaedic Surgeons •Kappa Delta Award (ACD 2/05)•Kappa Delta Young Investigator Award (ACD 2/05)•Orthopaedic Research and Education Foundation Clinical (ACD 2/05)•Research Award (ACD 2/05)Best Poster Award (12/07)American Academy of Pediatrics with AmericanSociety for Clinical InvestigationAmerican Aging Association Walter R. Nicolai Award (ACD 6/09)American Association of Anatomists R.R. Bensley Award in Cell Biology (ACD 6/08)American Association of Blood Banks •SBB Scholarship Awards (ACD 3/05)•Baxter Transfusion Medicine Scholarship Award (ACD 3/05)•AABB Fenwal TMF Scholarship Award (ACD 6/10)•Karl Landsteiner Memorial Award and Lectureship (ACD 10/12) (NEAC 7/16/10)American Association for Cancer Research (AACR) •AACR-ACS Award for Research Excellence in Cancer Epidemiology and Prevention (ACD12/08)•AACR-Aflac Scholarship-in-Training Award (ACD 12/06)•AACR-AstraZeneca Scholarship-in-Training Award (ACD 12/06)•AACR-GSK Outstanding Scholar Award (ACD 6/08) (NEAC 2/5/08)•AACR Lifetime Achievement in Cancer Research (ACD 6/09)•AACR-Merck Scholarship-in-Training Award (ACD 6/08)•AACR Sanofi-Aventis Scholar-in-Training Award (ACD 6/09)•AACR Scholar-in-Training by Susan G. Komen for the Cure (ACD 6/09)•Brigid G. Leventhal Scholar Award (ACD 6/07)•Bristol-Myers Squibb Oncology Scholar-in-Training Award (ACD 12/07) (NEAC 5/25/04)•Dorothy P. Landon AARC Prize for Translation Cancer Research (ACD 6/07) (NEAC3/27/07)•Margaret Foti Award for Leadership & Extraordinary Achievement (ACD 6/09) (NEAC5/26/09)•MEG Scholar in Training (ACD 6/08)•Prevent Cancer Foundation Award for Excellence in Cancer Research (ACD 6/10) (NEAC3/16/10)•Princess Takamatsu Memorial Lectureship Award (ACD 6/09) (NEAC10/13/09) American Association of Clinical Chemistry AACC Lectureship Award (ACD 5/05) (NEAC 5/17/05)American Association of Clinical Chemistry (AACC),Nutrition DivisionGarry Labbe Award (ACD 12/07)American Association of Colleges of Pharmacy Crystal APPLE Award (ACD 12/08) (5/12/09)American Association of Critical Care Nurses(AACCN)Circle of Excellence Award (ACD 12/11)American Association for Dental Research (AADR) AADR Distinguished Scientist Award (ACD 6/08) (NEAC 2/5/08)American Association of Immunologists •AAI-BD Biosciences Investigator Award (ACD 6/08)•AAI-Dana Foundation Award in Human Immunology Research (ACD 12/07)•AAI Trainee Achievement Award (ACD 6/09)American Association for Laboratory Animal Science •AALAS Poster Sessions Award, Laboratory Investigations Category (ACD 6/07)•George R. Collins Award (ACD 12/10)American Association of Neurological Surgeons Preuss Research Award (ACD 6/08)American Association for Pediatric Ophthalmology &StrabismusAAPOS Young Researchers Award (ACD 6/07)American Association for the Study of Liver Diseases Distinguished Service Award (ACD 2/06) (NEAC 4/14/09)American Chemical Society, Division of CarbohydrateChemistryNew Investigator Award (ACD 6/12)American Chemical Society, Division of Medicinal Chemistry •The Bristol-Myers Squibb Smissman Award (ACD 6/07) (NEAC 5/25/04) •Philip S. Portoghese Medicinal Chemistry Lectureship (ACD 6/12) (NEAC 7/10/12)American College of Chest Physicians CHEST Case Report Award (ACD 6/09) American College of Clinical Pharmacy Russell R. Miller Award (ACD 12/08)American College of Epidemiology Abraham Lilienfeld Award (ACD 6/06) (NEAC 3/16/06) American College of Neuropsychopharmacology •Daniel H. Efron Research Award (ACD 2/05)•Joel Elkes Research Award (ACD 2/05)•Julius Axelrod Mentorship Award (ACD 3/05)•Paul Hoch Distinguished Service Award (ACD 2/05)American College of Physicians •Award for Outstanding Work in Science as Related to Medicine (ACD 6/10)•John Phillips Memorial Award (ACD 12/11)•Mastership of the American College of Physicians (ACD 6/08) (NEAC 3/18/08)•National Associates Research Abstract Competition (ACD 6/06)•First Richard and Hinda Rosenthal Foundation Award (12/11)•Second Richard and Hinda Rosenthal Foundation Award (ACD 6/06) (NEAC 2/21/06) American College of Psychiatrists Stanley Dean Award for Research in Schizophrenia (ACD 2/05)American College of Rheumatology •ACR Awards of Distinction and Masters (ACD 2/05)•Rheumatology Fellow Award (ACD 6/06)American Diabetes Association •National Achievement Awards (ACD 3/05)•Young Investigator Travel Grant Award (ACD 6/09)American Dietetic Association Huddleson Award (ACD 12/07)American Federation for Medical Research Eastern Region Slienaholars (ACD 12/12)American Gastroenterological Association •The Master Award for Sustained Achievement in Digestive Sciences (ACD 6/07)•William Beaumont Prize in Gastroenterology (ACD 6/09) (NEAC 5/12/09) American Heart Association •Elizabeth Barrett-Connor Research Award in Epidemiology (ACD 2/05)•Eugene Braunwald Academic Mentorship Award (ACD 12/08) (NEAC 10/28/08)•Functional Genomics and Translational Biology Young Investigator Award (ACD 6/10)•Population Research Prize (ACD 12/09)•Trudy Bush Award (ACD 12/08)•Young Investigator Award (ACD 12/07)American Italian Cancer Foundation Prize for Scientific Excellence in Medicine Award (ACD 12/11) (NEAC 9/28/10) American Laryngological Association American Laryngological Association Award (ACD 6/06)American Journal of Human Genetics C.W. Cotterman Award (ACD 6/08)American Mensa Ltd Award for Excellence in Research (ACD 12/06)American Pharmacist Association APHA Distinguished Federal Pharmacist (ACD 6/08)American Physical Society Max Delbruck Prize in Biological Physics (ACD 9/12) (NEAC 7/24/12)American Physical Therapy Association •Jack Walker Award (ACD 2/05)•Section on Pediatrics Research Award (ACD 6/08)American Physiological Society •Epithelial Transport Group Young Investigator Award (ACD 6/08)•Renal Section’s Robert W. Berliner Award (ACD 6/09)American Psychiatric Association Blanche Ittleson Award for Research in Child and Adolescent Psychiatry (ACD 6/10) American Public Health Association David P. Rall Award for Advocacy in Public Health (ACD 12/07)American Public Health Association, GerontologicalHealth SectionJames G. Zimmer New Investigator Research Award (ACD 6/07)American Skin Association •David Martin Carter Mentor Award (ACD 6/12)•Research Scholar Awards (ACD 2/05)American Society of Andrology •Distinguished Andrologist Award (ACD 4/05)•Young Andrologist Award (ACD 12/11)American Society for Apheresis Best Abstract in Transplantation Award (ACD 6/08)American Society for Biochemistry and Molecular Biology (ASBMB) •ASBMB Oral Presentation Award (ACD 12/06)•Howard K. Schachman Public Service Award (ACD 12/10) (NEAC 11/9/10)American Society of Biomechanics (ASB) ASB Clinical Biomechanics Award (ACD 6/12) American Society for Blood & Marrow Transplantation New Investigator Travel Award (ACD 12/07)American Society for Bone & Mineral Research (ASBMR) •AIMM-ASBMR John Haddad Young Investigator Awards (ACD 8/08)•ASBMR Award for Outstanding Research in the Pathophysiology of Osteoporosis (ACD 8/08)•ASBMR Harold M. Frost Young Investigator Awards (ACD 8/08)•ASBMR Most Outstanding Abstract Award (ACD 8/08)•ASBMR President's Book Award (ACD 8/08)•ASBMR Young Investigator Awards (ACD 8/08)•ASBMR Young Investigator Travel Award (ACD 12/11)•Frederic C. Bartter Award (ACD 8/08)•Fuller Albright Award (ACD 8/08)•Gideon A. Rodan Excellence in Mentorship Award (ACD 8/08)•Louis V. Avioli Founders Award (ACD 8/08)•Shirley Hohl Service Award (ACD 8/08)•William F. Neuman Award (ACD 8/08)American Society for Clinical Investigation (ASCI) The ASCI Award (ACD 4/05) (NEAC 12/13/05)The American Society for Clinical Investigation withthe American Academy of PediatricsBest Poster Award (ACD 12/07)American Society of Clinical Oncology (ASCO) ASCO Merit Award (ACD 12/06)Pediatric Oncology Award and Lecture (ACD 12/11) (NEAC 5/26/11)American Society for Clinical Pharmacology and Therapeutics •Gary Neil Prize for Innovation in Drug Development (ACD 3/05)•Henry W. Elliott Award for Distinguished Service (ACD 3/05)•Leon I. Goldberg Young Investigator Award (ACD 3/05)•Oscar B Hunter Memorial Award in Therapeutics (ACD 3/05) (NEAC 11/25/05) •Rawls-Palmer Progress in Medicine Lecture and Award (ACD 3/05) •William B. Abrams Award in Geriatric Clinical Pharmacology (ACD 3/05)American Society for ExperimentalNeuroTherapeuticsJ. Stephen Fink Award (ACD 6/08)American Society for Gene & Cell Therapy Outstanding New Investigator Award (ACD 12/10)American Society of Hematology (ASH) •Abstract Achievement Award (Formerly ASH Travel & Merit Award) (ACD 6/08, 6/12)•William Dameshek Prize (ACD 12/09) (NEAC 11/24/09)American Society of Hospital Pharmacists Award for Sustained Contribution to the Literature of Pharmacy Practice (ACD 12/08) (NEAC11/25/08)American Society of Human Genetics •Allan Award (NEAC 3/21/06)•Semi-Finalist for each of the following 6 finalist Research Trainee Awards (ACD 9/09)•Predoctoral Basic Research Award (ACD 12/07)•Predoctoral Clinical Research Award (ACD 2/09)•Predoctoral Translational Research Award (ACD 2/09)•Postdoctoral Basic Research Award (ACD 2/09)•Postdoctoral Clinical Research Award (ACD 2/09)•Postdoctoral Translational Research Award (ACD 2/09)American Society for Investigative Pathology Chugai Award for Excellence in Mentoring and Scholarship (ACD 6/08) (NEAC 4/1/08) American Society for Microbiology (ASM) •Abbott Laboratories Award in Clinical & Diagnostic Immunology (ACD 6/08) (NEAC1/19/10)•Abbott/ASM Lifetime Achievement Award (ACD 12/11) (NEAC 5/26/11)•ASM Founders Distinguished Service Award (ACD 12/07)•bioMerieux Sonenwirth Award (ACD 2/05)•Corporate Activities Program Student Travel Grant (ACD 6/09)•Dade Behring MicroScan Young Investigator Award (ACD 6/08)•Maurice Hilleman Merck Award (ACD 12/11) (NEAC 3/1/11)•2007 ICAAC Young Investigator Award (ACD 12/07)•Promega Biotechnology Research Award (ACD 6/08) (NEAC 1/22/08)•Sanofi-Aventis U.S. Award (ACD 12/07) (NEAC 9/25/07)American Society for Neural Therapy and Repair The Bernard Sandberg Memorial Award for Brain Repair (ACD 6/07) (NEAC 5/22/07) American Society for Neuroradiology •ASNR Outstanding Presentation Award (ACD 12/09)American Society for Nutrition •The Davi Kritchesky Career Achievement Award (ACD 6/08)•ASN Norman Kretchmer Memorial Award Nutrition and Development (ACD 12/09) (NEAC6/23/09)American Society for Nutrition, Diet & CancerResearch Interest SectionEmerging Investigator Award (ACD 12/08)American Society for Nutritional Sciences Conrad A Elvehjem Award for Public Service in Nutrition (ACD 4/05)American Society for Pharmacology & Experimental Therapeutics •Bernard B. Brodie Award in Drug Metabolism (ACD 6/06)•ASPET - Astellas Awards in Translational Pharmacology (ACD 12/08) •Pharmacia-ASPET Award for Experimental Therapeutics (ACD 6/09) (NEAC 3/3/09)American Society for Virology 2007 Post Doctoral Fellow Travel Grant (ACD 12/07)American Statistical Association •Nathan Mantel Award for Lifetime Contributions to Statistics in Epidemiology (ACD 2/06)•New Investigator Award (ACD 12/07)American Statistical Association, the Institute of Mathematical Statistics, and the International Biometric Societies •Committee of Presidents of Statistical Societies Presidents’ Award (ACD 12/11) •Committee of Presidents of statistical Societies George W. Snedecor Award (ACD 12/11)American Stroke Association Thomas Willis Lecture (ACD 12/11) (NEAC 2/1/11)American Telemedicine Association President's Award for Advancement of Telemedicine (ACD 6/08) American Thoracic Society Carol Basbaum Award (ACD 10/12) (NEAC 6/27/12) American Thyroid Association Van Meter Award (ACD 12/06) (NEAC 8/5/08)American Veterinary Epidemiology Society Karl F. Meyer - James H. Steele Gold Cane Award (ACD 12/08) American Veterinary Medical Association Charles River Prize (ACD 12/06)Annemarie Opprecht Foundation Annemarie Opprecht Parkinson Award (ACD 12/08) (NEAC 10/14/08) Applied System Thinking Institute Inaugural ASysT Prize (ACD 12/08)Arthritis Foundation Lee C. Howley Sr. Prize for Arthritis Research (ACD 2/05) (NEAC 10/27/09) Association of American Physicians Kober Medal (ACD 6/07) (NEAC 4/10/07)Association of American Medical Colleges (AAMC) AAMC Herbert W. Nickens Award (ACD 12/08) (NEAC 11/11/08) Association of Black Women Physicians Lifetime Achievement Award (ACD 12/08)Association of Directors of Anatomic and SurgicalPathology and the US and Canadian Academy ofPathologyAutopsy Pathology Award (ACD 6/07)Association of Military Surgeons of the United States (AMSUS) •Pharmacy Awards (ACD 2/05)•James A. McCallam Award (ACD 12/08) (NEAC 11/11/08)Association for Research in Vision andOphthalmology (ARVO)•Camras Translational Award (ACD 6/12) (NEAC 6/5/12) Association of Rheumatology Health Professionals ARHP Merit Awards (ACD 2/05)Association of University Technology Managers(AUTM)Howard Bremer Scholarship (ACD 6/08)Bar Ilan University, Cancer, AIDS & ImmunologyResearch (CAIR) InstituteC.A.I.R. Institute Science Award (ACD 12/10) (10/26/10) Becton Dickinson Biosciences Rolduc BD Biosciences Poster Prize (ACD 6/08) Biocore/BioTechniques Award for Excellence (Poster Award) (ACD 12/06) BioMed Central Journal of Medical Case Reports Award (ACD 12/08)Biophysical Society •Avanti Award (ACD 2/05) (NEAC 1/16/07)•Distinguished Service Award (ACD 2/05)•Emily M. Gray Award (ACD 2/05)•Fellow of the Biophysical Society (ACD 2/05)•Founders Award (ACD 2/05)•Margaret Oakley Dayhoff Award (ACD 2/05)•Michael & Kate Barany Award for Young Investigators (ACD 2/05)Board of Directors of City Trusts, Philadelphia, PA John Scott Medal (ACD 12/10) (NEAC 11/19/10)Bones & Teeth Gordon Research Conference Bones and Teeth Gordon Research Travel Awards (ACD 12/07)Brain and Behavioral Research Foundation •Bipolar Mood Disorder Prize (ACD 12/11) (NEAC 9/13/11)•Lieber Prize for Schizophrenia Research (ACD 12/11) (NEAC 9/13/11)•Ruane Award for Child and Adolescent Psychiatric Research (ACD 12/11) (NEAC 9/13/11) British Association for Psychopharmacology Wyeth Psychopharmacology Awards (Pre-clinical Psychopharmacology and ClinicalPsychopharmacology) (ACD 12/07)British Blood Transfusion Society James Blundell Award (ACD 3/05)Bristol-Myers Squibb Foundation Distinguished Achievement Awards (ACD 2/05)Burroughs Wellcome Fund Career Awards in Biomedical SciencesButler Center for Research Hazelden Foundation Dan Anderson Research Award (ACD 6/09) (NEAC 3/3/09)Caledonian Research Foundation Caledonian Prize Lectureship (ACD 12/06) (NEAC 6/13/06)Canada Gairdner Global Health Canada Gairdner Global Health Award (12/08)Cancer Research Institute William B. Colay Award for Distinguished Research in Basic and Tumor Immunology (ACD6/12) (NEAC 12/23/11)Case Western Research University InamoriInternational Center for Ethics and ExcellenceInamori Ethics Prize (ACD 12/11)Castilla del Pino Federation Castilla del Pino Award for Achievement in Psychiatry (ACD 3/05) (NEAC 2/7/06) (See endnote)Center for American Women and Politics •Good Housekeeping Award for Women in Government (ACD 2/05)•Housekeeping/Wyeth Award for Women's Health (ACD 2/05)The Centro Mangrella Foundation Mauizio Mangrella Award in Neuroscience (ACD 12/06) (NEAC 9/5/06)CERM, Florence Italy (Italian Chemical Society) City of Florence Award for the Molecular Sciences for the Year 2009 (ACD 6/09) (NEAC2/3/09)Chemical Society of Washington Hillebrand Prize (ACD 6/07)Christopher Columbus Fellowship Foundation (US Government agency) •Agriscience Award (ACD 3/11) (cash prize is not a gift) •Frank Annuzio Awards (ACD 4/05)•Life Sciences Award (ACD 3/11) (cash prize is not a gift) •Homeland Security Awards (ACD 4/05)City of Hope National Medical Center Rachmiel Levine Scientific Achievement Award (ACD 6/12) City Trusts Board of Directors John Scott Medal (ACD 12/10)Clinical Ligand Assay Society Distinguished Scientist Award (ACD 2/06)Cognitive Neuroscience Society George A Miller Prize in Cognitive Research (ACD 4/05)The College on Problems of Drug Dependence J. Michael Morrison Award (ACD 12/06) (NEAC 5/27/08) Collegium International Neuro-psyco-pharmacologicumYoung Investigator Award (ACD 12/06)Colleguim Ota-Rhino Larynogologicum AmicitiaeSacrum2007 Acta Oto-Laryngologicia Prize (ACD 12/07) (NEAC 8/28/07)Columbia University of Mailman School of PublicHealthFrank A. Calderone Prize in Public HealthCommissioned Officers’ Association Mabel Mae Wagner Nursing Award (ACD 12/09)Comprehensive Cancer Center/Arthur G. JamesHerbert & Maxine Block Memorial Lectureship Award (ACD 12/06) (NEAC 5/22/07) Cancer Hospital & Richard J. Solove ResearchInstitute at Ohio State UniversityComtecmed CODHy Best Abstract Award, Obesity Category (ACD 12/10)Conchita Rabago de Jimenez Diaz Foundation Jimenez Diaz Memorial Lecture (ACD 6/07) (NEAC 4/24/07)Conquer Fragile X CFXF Rising Star Award (Best Poster) (ACD 12/07)Depression and Bipolar Support Alliance •Gerald L. Klerman Investigator Award (ACD 6/08) (NEAC 5/13/08)•Gerald L. Klerman Senior Investigator Award (ACD 6/08) (NEAC 5/13/08) Dermatology Nurses' Association Dermik Laboratories Career Mobility Scholarship (ACD 2/05)Desert AIDS Project Science and Medicine Award (ACD 12/08) (NEAC 9/16/08)Elsevier Brain Research Most Cited Paper Awards (ACD 12/11)Endocrine Society •Endocrinology & Molecular Endocrinology Student Author Awards (ACD 6/08)•Distinguished Educator Award (ACD 8/08)•Distinguished Physician Award (ACD 8/08) (NEAC 9/2/08)•Edwin B. Astwood Award Lecture (ACD 8/08)•Ernst Oppenheimer Award (ACD 8/08)•Fred Conrad Koch Award (ACD 8/08)•Richard E. Weitzman Memorial Award (ACD 8/08)•Robert H. Williams Distinguished Leadership Award (ACD 8/08)•Sidney H. Ingbar Distinguished Service Award (ACD 8/08)•Endocrine Society Travel Awards (ACD 12/08)Environmental Mutagen Society •Alexander Hollaender Award (ACD 6/10)•Environmental Mutagen Society Award (ACD 12/10) (NEAC 7/8/08) European Association of Perinatal Medicine Maternite Prize (ACD 12/12) (NEAC 7/24/12)European Institute of Oncology European Institute of Oncology Breast Cancer Award (ACD 12/08) (NEAC 9/16/08)EWSI’s Influenza Award for Young Scientists (ACD 12/11)European Scientific Working Group on Influenza(ESWI)European Society of Genes and Cell Therapy Young Investigator Award (ACD 12/12)FEBS Journal FEBS Journal Prize (ACD 12/06) (NEAC 10/13/06)Federation of American Societies for ExperimentalExcellence in Science Award (ACD 3/05)BiologyFondation de France Jacques Monod Award (ACD 12/07) (NEAC 9/25/07)Fondation Jean-Pierre Lecocq Jean-Pierre Lecocq Prize (ACD 6/06)Fondazione Raffaella Becagli FIRMO Parathyroid Award (ACD 6/10) (NEAC 5/25/10)Fonds National de la Recherche Scientifique Balillet Latour Health Prize in Immunity and Infectious Diseases (ACD 2/06) Foundation for the NIH and the NIH Virology InterestNormal P. Saltzman Award in Virology (ACD 12/06)GroupFranklin Institute Bower Award and Prize for Achievement in Science (ACD 6/10)French Association of Cancer Research Leopold Griffuel Prize (ACD 2/06) (NEAC 6/28/05) (See end note)Gairdner Foundation Gairdner Foundation International Awards (ACD 2/05)GEICO •Fire Prevention and Safety Award (ACD 6/07)•Physical Rehabilitation Award ACD 6/07)•Substance Abuse Prevention and Treatment Award (ACD 6/07)•Traffic Safety and Accident Prevention Award (ACD 6/07)General Motors Cancer Research Foundation GM Cancer Research Prizes (ACD 2/05)German Society of Virology Leoffler-Frosch Award ACD (3/05)Gerontological Society of America Nathan Shock New Investigator Award (ACD 12/06)Global Health Council Dr Nathan Davis International Awards (ACD 2/05)Hans Popper Hepatopathology Society Pathologist-in-Training Award (ACD 12/08)Harvard Medical School Ruth and William Silen Award (ACD 12/07)Harvard School of Public Health Marvin Zelen Leadership Award (ACD 12/06)Harvard University Innovations in American Government Program (ACD 2/05)Health Improvement Institute Award for Excellence in Human Research (ACD 6/08)Dr. H.P. Heineken Foundation and Alfred HeinekenFondsen FoundationHeineken Prizes (ACD 6/12)Helen Keller Foundation for Research and Education The Helen Keller Prize for Vision Research (ACD 6/08) (NEAC 1/22/08) Hematology/Oncology Pharmacy Association •HOPA Award of Excellence (ACD 12/09)•2012 HOPA New Practitioner Award (ACD 6/12)Henry M. Jackson Foundation for the Advancement ofMilitary MedicineHarold L. Steward Fund for Experimental Pathology (ACD 6/12)HIV Medicine Association of the Infectious DiseaseSociety of America2007 HIVMA Emerging Leader in Clinical Education Award (ACD 12/07) (NEAC 9/11/07)Hospital for SickKids (Toronto), Programme for Global Pediatric Research Programme for Global Paediatric Research (PGPR) Award for Outstanding Contributions to Global Child Health (ACD 6/12) (NEAC 4/10/12)Illinois Society of Microbiology Pasteur Award (ACD 6/08)Intercultural Cancer Council ICC Hope Award (ACD 12/08)International Association of Therapeutic DrugMonitoring and Clinical Toxicology (IATDMCT)IATDMCT Patsalos Prize (ACD 12/11) (NEAC 9/26/11)International Association for Dental Research (IADR)& American Association for Dental Research (AADR) •Salivary Research Award (ACD 12/06)•IADR Distinguished Scientist Award for Oral Medicine and Pathology Research (ACD 6/07) •IADR Distinguished Scientist Award, Isaac Schour Memorial Award (ACD 6/09)•IADR Distinguished Scientist Award in Oral Biology (ACD 12/10) (NEAC 6/22/10)International BioIron Society (IBIS) •Gunshin Levy Award (ACD 6/12)•Novartis Presidents Award (Best Young Scientist Presentation) (ACD 12/07) (NEAC8/28/07)International Clinical Cytometry Society Wallace H. Coulter Award (ACD 12/10) (NEAC 11/23/10)International Congress of GRS and the IGF Travel Award (ACD 12/08)International Congress of Radiation Research (ICRR) ICRR Travel Award (ACD 6/08)International Cytokine Society •Post-Doctoral Investigator Award (ACD 12/07)•Honorary Life Member Award (ACD 12/11) (NEAC 3/1/11)•Outstanding Scholar Award (ACD 12/08)•Young Investigator Award (ACD 12/08)International Feline Retroviruses ResearchSymposiumYoung Investigator Award (ACD 6/09)International Foot and Ankle Biomechanics The Best Paper Award (ACD 6/09)International Mammalian Genome Society 2006 International Mammalian Genome (ACD 6/07)International Personnel Management Association(IPMA)Linda Trunzo Humanitarian Award (ACD 12/06)International Society for Biological Therapy of Cancer Presidential Travel Award (ACD 6/09)International Society of Biomechanics (ISB) Clinical Biomechanics Award (ACD 12/11)International Society of Blood Transfusion Presidential Award (ACD 6/12) (NEAC 6/25/12)International Society of Dermatopathology The Sabine Kohler Lecture and Award (ACD 12/11) International Society for Eye Research •Endre A. Balazs Prize (ACD 2/05)•Ernst H. Barany Prize (ACD 2/05) International Society for Heart Research ISHR Distinguished Leader Award (ACD 6/10)International Society for Interferon & Cytokine Research •Millstein Award (ACD 3/05) (NEAC 10/19/04)•Seymour and Vivian Milstein Travel Award (ACD 6/10) (NEAC 11/11/08)International Society for the Study of Xenobiotics ISSX North American Scientific Achievement Award (ACD 12/06)Institute of Medicine, National Academies of Science •Rhoda & Bernard Sarnat International Award in Mental Health (ACD 2/05)•Gustav O. Lienhard Award (ACD 2/05)James t. and Sarah F. Fries Foundation Elizabeth Fries Health Education Award (ACD 12/12) (NEAC 10/23/12)Japan Rheumatism Foundation Japan Rheumatism Foundation International Award (ACD 6/06) (NEAC 2/12/06)Japan Society for the Promotion of Science International Prize for Biology (ACD 12/09)(May accept honor but not the cash prize) Jellinek Memorial Fund Jellinek Memorial Award (ACD 12/07) (NEAC 6/19/07)Johns Hopkins University Bloomberg School of PublicHealthMargaret Merrell Award for Excellence in Research (ACD 12/06)Johns Hopkins University School of Medicine Research Festival Top Abstract Award (ACD 12/08)Keystone Symposia •Anita Roberts Young Scientist Scholarship Award (ACD 6/08)•Global Health Travel Awards and Travel Scholarships (ACD 12/07)•Keystone Symposia Minority Scholarship Award (ACD 12/07)Kinship Foundation Searle Scholars Program (ACD 2/06)Korean-American Scientists and EngineersAssociationKUSCO-KSEA Scholarship for Graduate Students in the US (ACD 12/08) Kuratorium des Weitbrecht-Wissenschaftspreis Hans-Joerg-Weitbrecht-Wissenschaftspreis (ACD 6/09) (NEAC 5/26/09)Laurentian Conference of Rheumatology Roger Demers Prize (ACD 6/08) (NEAC 4/1/08)Lawson Wilkins Pediatric Endocrine Society Human Growth Foundation Award (ACD 6/10)Leukemia and Lymphoma Society Nurse of the Year Award (ACD 6/08)Linus Pauling Institute at Oregon State University Linus Pauling Institute Prize for Health Research (ACD 6/07)Lymphoma Foundation of America Young Scientist Award (ACD 6/08)Maureen & Mike Mansfield Foundation Mansfield Fellowship Program (ACD 2/05)Massachusetts Institute of Technology •Edward M Scolnick Prize in Neuroscience Research (ACD 4/05) (NEAC 3/22/05)•The $500,000 Lemelson MIT Award for Invention & Innovation (ACD 12/06)•The $100,000 Lemelson MIT Award for Sustainability (ACD 12/06)MD Anderson Cancer Center Annual John Mendelssohn AwardMedical Laboratory Immunologists Erwin Neter Award (ACD 12/10)Medical Library Association •Lucretia W. McClure Excellence in Education Award (ACD 6/07)•MLA Research Award (ACD 12/11)•Thomson Scientific/Frank Bradway Rogers Information Advancement Award (ACD 2/05) Memorial Sloan-Kettering Cancer Center •Paul Marks Prize for Cancer Research (ACD 4/05)•Niehaus Southworth Weissenbach Award in Preventive Cancer Genetics (ACD 12/10) Metropolitan District of Columbia Respiratory SocietyResearchBest Poster for Basic Science Research Award (ACD 12/10)Microscopy Society of America (MSA) MSA Presidential Student Award (ACD 6/07)Mid-Atlantic Association of Blood Banks Mary C. Doerr Meritorious Services Award (ACD 12/08)Millennium Prize Foundation Millennium Technology Prize (ACD 4/05)Myrovlytis Trust Myrovlytis Trust Travel Award - BHD Symposium (ACD 12/08)。

Pearson Edexcel Mathematics Awards 产品说明书

The Pearson Edexcel Mathematics Awards (Level 1, Level 2 and Level 3)Frequently Asked Questions1. What are the Pearson Edexcel Mathematics Awards?The Pearson Edexcel Mathematics Awards are a suite of stand-alone academicqualifications in mathematics which support the GCSE, International GCSE, BTEC and GCE qualifications that are offered in schools and colleges.Each award:•takes approximately 60-70 hours to deliver as a stand-alone (roughly the size of halfa GCSE)•is assessed externally through written papers•is awarded pass or unclassified•is available at different levels (Level 1, Level 2 or Level 3)2. What Pearson Edexcel Mathematics Awards are available?The following Awards have been accredited:•Pearson Edexcel Level 1 Award in Number and Measure•Pearson Edexcel Level 2 Award in Number and Measure•Pearson Edexcel Level 2 Award in Algebra•Pearson Edexcel Level 3 Award in Algebra3. Which students are these qualifications aimed at?These qualifications are aimed at students who:•need to develop their mathematical skills in a particular area (e.g. number and measure or algebra) and build confidence in the subject before progressing to GCSE or GCE mathematics or further study•want to gain a qualification which demonstrates their mathematical ability.4. Do these qualifications attract performance table points?None of the qualifications receive performance table points.5. How are the Pearson Edexcel Mathematics Awards assessed?The Pearson Edexcel Mathematics Awards are externally assessed. The table below shows the structure of the written papers.More information can be accessed via our dedicated webpage at /edexcelmathsaward.6. Do the level 3 awards get UCAS points?Yes the Level 3 Award in Algebra does attach a total of 3 UCAS points. More information can be found on page 143 of the UCAS Tariff Table document.7. When are the examinations available for students to take?The Pearson Edexcel Awards suite is available in January and May every year.8. How and when are results published?Students will be awarded pass or unclassified. Results from Level 1 and Level 2examinations taken in May will be published on GCSE results day in August. Results from Level 3 examinations taken in May/June will be published on GCE results day in August.Results from examinations taken in January will be published mid-March.9. When can I start teaching these qualifications?The Pearson Edexcel Awards in Number and Measure have been available for firstteaching from September 2011 and the Pearson Edexcel Awards in Algebra have been available for first teaching from October 2012. The content and assessment of thequalifications have been designed to fit flexibly in to the programme of delivery forschools and colleges and because each Award only takes 60-70 guided learning hours you can start straight away or wait until later in the year.10. Do I need approval to offer these qualifications at my centre?If you already run any GCSE or GCE qualifications in your centre then you do not need any additional approval to run these qualifications. If you are not an approved Pearson Edexcel centre, you can apply for approval athttps:///content/demo/en/support/support-topics/centre-administration/becoming-a-centre.html11. How do I make entries for these qualifications?Entries should be made in the same way as entries are made for other qualifications.Our information manual contains all the practical information you need to deliver our qualifications.The table below shows details of the entry codes.More information can be accessed via our dedicated webpage at /edexcelmathsaward.12. What are the entry fees for these qualifications?Entry fees are available on our website here.13. What support is available for these qualifications?•Web support – our dedicated qualification webpages at /edexcelawardnumber and /edexcelawardalgebra. Genericinformation about the suite can be found at /edexcelmathsaward •Mathematics Emporium – sign up for the mailing list to ensure you have all the relevant information and support when you need it. Also register for an account at for access to over 6,000 documents relating to all ourmathematics qualifications and follow us on twitter @EmporiumMaths for all thelatest news and updates from our subject partners.•Teacher support materials and resources – The following teaching and learning support is available for the Edexcel Awards qualifications:- content mappings to the reformed GCSE and GCE qualifications- scheme of work- practice paper and mark schemes- past papers, mark schemes and grade boundaries- paid-for workbooksAll of this support is available under ‘course material’s on each of the qualificationwebpages.•ResultsPlus – as with our GCSE and GCE mathematics qualifications, our free online results analysis tool gives teachers a detailed breakdown of your students’performance in the Awards. More information about ResultsPlus services can befound at /ResultsPlus14. How long will these qualification continue to be offered?These qualifications will continue to be offered indefinitely. If this changes at any time, you will be updated accordingly.15. How can I find information regarding funding for this qualification?All information regarding funding can be found on our website here.More information can be accessed via our dedicated webpage at /edexcelmathsaward.。

考博学术成就总结模板可打印

考博学术成就总结模板可打印1. 引言本文旨在总结我的考博学术成就，并提供一个可打印的模板，供其他人参考。

在此过程中，我将回顾我在研究中取得的成就，包括论文发表、学术交流等。

2. 论文发表- 我在考博期间共发表了X篇学术论文，其中包括国内外期刊和会议论文。

这些论文涵盖了我在研究领域的重要发现和贡献。

- 在发表过程中，我积极参与同行评审，并采纳评审意见进行修改，以确保论文质量和学术价值的提升。

- 在多个国际会议上，我也有机会展示我的研究成果，与其他学者进行深入的交流和讨论。

3. 学术交流- 我积极参与学术交流活动，包括参加学术会议、研讨会和研究小组等。

- 在学术会议上，我不仅展示了自己的研究成果，还倾听了其他学者的研究报告，与他们进行学术讨论和思想碰撞。

- 我还加入了学术研究小组，与其他研究人员共同合作，进行深入的探讨和研究。

4. 研究成果评价- 我的研究成果受到了同行专家的高度评价，其中一些成果还被其他学者引用和借鉴。

- 我的论文在核心期刊、高水平国际刊物上发表，证明了其学术影响力和质量。

- 我相信这些研究成果和学术交流经验将对我的未来学术发展起到积极的推动作用。

5. 可打印模板本文提供一个可打印的模板，以供其他人参考和使用。

这个模板包括了总结自己学术成就的各个方面，帮助他们整理和归纳自己的研究成果，更好地展示自己在学术领域的突出表现。

6. 结论通过总结自己的考博学术成就，并提供可打印的模板，我希望能够鼓励和帮助其他人在学术道路上获得更好的成就。

同时，我也对自己在研究中的努力和取得的成果感到满意和自豪。

请注意：此文档的内容仅供参考，请酌情使用和修改。

学术道德修养8-27章习题答案全

可编辑修改精选全文完整版学术道德修养8-27章习题答案1【判断题】大学建立荣誉制度的初衷旨在预防大学生考试作弊。

正确答案：√2【判断题】在科学家之间和科学与社会之间，信誉与相互信任尤为重要。

正确答案：√3【判断题】科学研究与学术工作与人类其他活动一样，均建立在诚信之上。

正确答案：√1【单选题】以下哪些行为符合学术诚实三原则：A、把上届学长的课程论文当作自己应该完成的作业交给老师。

B、将老师的课堂笔记整理成论文并署上自己的名公开发表。

C、在实验中，为了让实验结果更漂亮而有选择地使用数据。

D、在著作的后记中对那些提出过修改建议的同行表示感谢。

正确答案：D2【判断题】所有的数据和文献应真实而公正地呈现。

正确答案：√3【判断题】小保方晴子在研究过程中存在“捏造”和“篡改”图片行为，有违学术诚实。

正确答案：√1【单选题】在学习的过程中，以下哪种做法是不诚实的：A、在做作业时，遇到困难向老师请教。

B、在做作业时，独立完成应该完成的作业。

C、为了尽快完成作业，参考高年级学长做过的同样的作业。

D、老师布置的作业量太大时，一方面努力认真完成，另一方面找机会向老师反映作业量过大这一实际情况。

正确答案：C2【单选题】在学习的过程中，以下哪种做法是诚实的行为：A、上课时，讲解老师要求自己讲解的内容时参考同学的阅读笔记。

B、考试时，将考试课程的课堂笔记等按规定不可以带入考场的东西带进考场，以备不时之需。

C、考试时，遇到不会的题目时，宁可空着，也不抄袭。

D、在完成老师要求的读书报告时，直接搜集别人写的几遍相关报告，重新组合后当作业交给老师。

正确答案：C3【单选题】以下说法中，哪一种是正确的：A、诚实学习就是严格按照老师的要求完成作业、论文和考试等学习任务。

B、小组合作完成作业时，主要由会做的同学完成，不会做的同学可以不做或尽量少做。

C、小组合作完成作业时，某位同学不能完成自己应该完成的工作时，可以请小组的其他同学帮忙完成。

pku北大学子毕业生去向

环境学院心理学系心理学系心理学系心理学系心理学系心理学系新闻与传播学院新闻与传播学院新闻与传播学院新闻与传播学院新闻与传播学院新闻与传播学院新闻与传播学院新闻与传播学院新闻与传播学院新闻与传播学院新闻与传播学院新闻与传播学院新闻与传播学院新闻与传播学院新闻与传播学院新闻与传播学院新闻与传播学院新闻与传播学院新闻与传播学院新闻与传播学院新闻与传播学院新闻与传播学院新闻与传播学院新闻与传播学院新闻与传播学院新闻与传播学院
美国中国中国美国中国中国美国美国香港中国中国美国美国中国美国美国美国中国美国美国中国中国美国美国中国美国中国英国美国中国中国美国中国
55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87
化学与分子工程学院化学与分子工程学院化学与分子工程学院化学与分子工程学院化学与分子工程学院化学与分子工程学院化学与分子工程学院化学与分子工程学院化学与分子工程学院化学与分子工程学院化学与分子工程学院化学与分子工程学院化学与分子工程学院生命科学学院生命科学学院生命科学学院生命科学学院生命科学学院生命科学学院生命科学学院生命科学学院生命科学学院生命科学学院生命科学学院生命科学学院生命科学学院生命科学学院生命科学学院生命科学学院地球与空间科学学院地球与空间科学学院地球与空间科学学院地球与空间科学学院
姓名
性别
院系
国家地区
22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54

1、下载文档前请自行甄别文档内容的完整性，平台不提供额外的编辑、内容补充、找答案等附加服务。
2、"仅部分预览"的文档,不可在线预览部分如存在完整性等问题,可反馈申请退款(可完整预览的文档不适用该条件!)。
3、如文档侵犯您的权益，请联系客服反馈,我们会尽快为您处理(人工客服工作时间：9:00-18:30)。

学术之星
为了营造积极健康的校园学术氛围，充分展示我校广大研究生学术科研能力和科技创新成果，研究生学院研究生创新中心于2011年10月13日—11月13日举办了第四届研究生“学术之星”评选活动。

活动旨在表彰积极参与科研的优秀研究生，激励其在学术上勇于攀登、积极创新、与时俱进的精神，以激发广大研究生的科研热情，提高我校研究生的学术水平。

在此次评选活动中，涌现出了大量科技创新成果，充分彰显了我校研究生学术科研能力和学术创新精神。

经过层层筛选，最终评选出七位学术之星，为我校广大研究生树立了学习榜样。

现将学术之星及其研究成果予以公示：
（1）刘家顺土木与交通学院
刘佳顺，男，团员，土木与交通学院2009级硕士研究生，研究方向为环境岩土工程。

攻读硕士期间共发表论文9篇，其中国内核心期刊6篇，国内一般刊物1篇，会议论文集2篇，ISTP收录2篇。

参与了辽宁省优秀人才计划《风积土冻胀与融沉特性及其工程防治措施的研究》、横向课题《辽西地区钢筋混凝土钢架拱桥加固技术研究》和《辽西地区T型梁桥加宽加固工程技术研究》三项，纵向课题《高速铁路风积土路基的振（震）陷变形试验研究》和《冻融和渗流耦合作用下风积土路基结构性演变的研究》两项。

张向东，教授，1983年毕业于辽宁工程技术大学（原阜新矿业学院），获工学学士学位；1986年毕业于东北大学（原东北工学院），获工学硕士学位；1997年毕业于东北大学资源与土木工程学院，获工学博士学位。

现为辽宁工程技术大学岩土工程学科带头人，土木与交通学院院长和岩土工程研究所所长，为辽宁省中青年骨干教师、辽宁省"百千万人才工程"百人层次人选、中国岩石力学与工程学会东北分会理事、中国岩石力学与工程学会地面岩石工程专业委员会委员、中国煤炭学会矿井建设专业委员会委员、辽宁省土木建筑工程学会理事。

（2）富佳兴机械工程学院
富佳兴，男，中共党员，机械工程学院2009级硕士研究生，研究方向为机械系统动态特性与控制。

攻读硕士期间共发表论文2篇，其中国际期刊1篇，国内核心期刊1篇，ISTP收录1篇，EI收录1篇，参与了国家重点技术创新项目《振动设备动力学性能及结构动态设计方法的研究》，研究生科研立项《道内壁爬行机器人的研究》，2009年10月参加辽宁省挑战杯科技竞赛获二等奖，获得实用新型专利共10项，如可控粒度掘进机截割头、多用途静力学组合教具、管道清洁机器人等。

何凡，教授，主要从事机械设计及理论的研究与教学工作。

主持完成“热电厂循环流化床锅炉省煤器变形磨损机理研究”、“500KV高压输电线路绝缘子带电清扫设备的研制”等多项课题。

主持项目“海州立井箕斗罐笼改造”获阜新矿业集团科技进步一等奖、“清河门矿立井通风系统改造工程”获阜新市优秀设计一等奖。

获得《反井爆破架》等国家专利3项，主编《机械原理与机械设计实验》等教材6部，主编《机械设计基础》等多媒体教学课件2部，在《中国工程机械学报》等刊物发表论文10余篇。

（3）李涛矿业学院
李涛，男，中共党员，矿业学院2009级硕士研究生，研究方向为矿山压力及其控制。

攻读硕士期间共发表论文8篇，其中国内核心期刊3篇（有2篇是第一作者完成），国内一般期刊3篇（全部为第一作者完成），会议论文集2篇，ISTP 收录1篇，EI收录1篇，参与了河北省科学技术成果《开滦矿区近距离煤层群上行安全开采理论与实践研究》。

张宏伟，教授，德国克劳斯达尔工业大学高级访问学者，国家安全生产专家，煤炭“653”工程首席专家，现任辽宁工程技术大学环境科学与工程学院院长，中国煤炭学会开采专业委员会委员。

主要研究方向是矿井动力现象预测和矿山压力及其控制。

主持完成了“煤与瓦斯突出危险性的模式识别与概率预测技术”等国家“九五”、“十五”、“十一五”、“973”、国家自然科学基金、教育部博士点基金、企
业合作等科研课题40余项。

获得了中国煤炭工业协会科学技术一等奖等7项省部级奖励。

（4）魏晓刚建筑工程学院
魏晓刚，男，中共党员，建筑工程学院2009级硕士研究生，研究方向为工程结构抗震与防灾。

攻读硕士期间共发表论文16篇，其中中文核心期刊8篇，外文期刊4篇，国内会议论文集1篇，国际会议论文集3篇，并且EI收录4篇，ISTP 收录3篇。

曾受邀参加国内外重要学术会议五次，并三次在分组讨论中做学术交流报告，参与校研究生科研立项，并取得《采动区地震—开采沉陷变形对建筑物耦合作用机理研究》等科研成果。

刘书贤，教授，从事结构工程、岩土工程学科的教学、科研工作，主要研究方向为新型结构设计理论、钢筋混凝土结构、建筑灾害的防护与处理。

现任葫芦岛校区基建办主任。

主持相关方向的科研项目20余项，先后获辽宁省科技进步奖二等奖1项，三等奖1项，黑龙江省科技进步奖二等奖1项，获市级科技进步一、二等奖7项。

在各类学报上发表学术论文40余篇。

先后为研究生、本科生授课20余门。

主编教材2部，副主编教材2部，参编教材1部。

（5）冯本成电气与控制学院
冯本成，男，预备党员，电气与控制学院2009级硕士研究生，研究方向为电力电子平磁集成及无源集成。

攻读硕士期间共发表论文9篇，其中国内核心期刊3篇，国内一般期刊3篇，会议论文集3篇，参与了国家自然科学基金、辽宁省高校创新团队支持计划（获辽宁省优秀科研成果）、辽宁工程技术大学第三届研究生科研立项，获得了步进式数控电液阀控制装置和交流电动机综合保护装置两项实用新型专利。

杨玉岗，教授，归国留学人员，1997年毕业于清华大学电机系，获工学博士学
位，1998年—2001年在华为公司从事开关电源研发工作，任电磁研究室主任，2004年9月~12月赴德国克劳斯塔尔工业大学电力工程系做高级访问学者，2006年赴美国弗吉尼亚理工大学电力电子国家中心（CPES）做高级访问学者。

国家自然科学基金项目评议人，入选辽宁省“百千万人才工程”千人层次。

出版著作2部，发表论文40余篇，获得中国专利5项，辽宁省自然科学技术学术成果奖等4项。

（6）高茉电子与信息工程学院
高茉，女，预备党员，电子与信息工程学院2009级硕士研究生，研究方向为信号检测与估计。

攻读硕士期间共发表论文9篇，其中国际刊物4篇，国内核心期刊1篇，国内一般刊物2篇，会议论文集2篇，SCI收录1篇，ISTP收录3篇，EI收录4篇，CSSCI收录1篇，参与了校第三届研究生科研立项《老虎台矿动力灾害检测数据集成专家决策系统研究》，获得了2011全国虚拟仪器设计大赛参赛奖。

冀常鹏，教授，辽宁省优秀青年骨干教师，《International Journal of Convergence Computing》主编；《Journal of Computers》特邀编辑；《中国通信》、《电讯技术》、《中国科技论文在线》等特邀审稿专家，IEEE及WASE会员。

主持或参与完成各级科研项目30余项。

发表学术论文90余篇，其中SCI、EI、ISTP 检索40余篇。

出版学术著作共3部（《单片机智能控制技术》，国防工业出版社2007；《现代通信电源》，国防工业出版社2010；《AVR单片机GSM/GPRS 应用技术》，国防工业出版社2011）。

获得国家发明专利3项，实用新型专利11项。

（7）徐雅臣工商管理学院
徐雅臣，女，中共党员，工商管理学院2009级硕士研究生，研究方向为产业组织。

攻读硕士期间共发表论文9篇，其中国内核心期刊1篇，国内一般期刊5
篇，会议论文集3篇，ISTP收录3篇，EI收录1篇，CSSCI收录1篇。

曾参与《山东货源矿业公司友众煤矿文化研究》和《大唐国际胜利东二号露天煤矿项目员工培训及考试系统开发》两项省级项目申请。

赵宝福，教授，管理科学与工程学科博士生导师，区域经济学学科带头人。

现任辽宁工程技术大学工商管理学院院长，中国中小企业研究会理事，同时兼任两个企业的独立董事。

长期从事教学科研和管理工作，出版专著一部、教材四部、中英文论文30余篇。

主持完成了省部级及横向课题20多部。

曾获煤炭协会科技进步二等奖、阜新市科技进步一等奖、二等奖等多项科研奖励。

目前在研科研项目6项。