Post inoculation in the structural control of ductile cast iron
资格考试哈工大年夜荷载与结构设计方法
being considered
Statistical Uncertainty Uncertainty arising from estimating parameters based on a
Conclusions
Many sources of uncertainty are inherent in structural planning, design, construction, and operation.
The parameters of the loading and the load-carrying capacities of structural members are not deterministic quantities, they are random variables, and therefore absolute safety of structures cannot be achieved.
Chapter 1 Introduction
Chapter 1: Introduction Contents 1.1 Uncertainties in Structural Engineering 1.2 Objectives and Tasks of Structural Design 1.3 Development of Structural Design Method 1.4 Probability Levels of Structural Design 1.5 Probability Foundations for Structural Reliability Theory
带电荷缺陷的迁移
This article appeared in a journal published by Elsevier.The attached copy is furnished to the author for internal non-commercial research and education use,including for instruction at the authors institutionand sharing with colleagues.Other uses,including reproduction and distribution,or selling or licensing copies,or posting to personal,institutional or third partywebsites are prohibited.In most cases authors are permitted to post their version of thearticle(e.g.in Word or Tex form)to their personal website orinstitutional repository.Authors requiring further informationregarding Elsevier’s archiving and manuscript policies areencouraged to visit:/authorsrightsStability and migration of charged oxygen interstitials in ThO 2andCeO 2H.Y.Xiao a ,⇑,Y.Zhang b ,a ,W.J.Weber a ,baDepartment of Materials Science &Engineering,University of Tennessee,Knoxville,TN 37996,USA bMaterials Science &Technology Division,Oak Ridge National Laboratory,Oak Ridge,TN 37831,USAReceived 27June 2013;received in revised form 9August 2013;accepted 4September 2013Available online 30September 2013AbstractDensity functional theory calculations have been carried out to study the stability and migration of charged oxygen interstitials in ThO 2and CeO 2.The calculations demonstrate that the oxygen interstitial is likely to lose electrons under p -type conditions and gainelectrons under n -type conditions.Neutral O 0split and singly positive O þsplit O–O h 110i split interstitials,and doubly negative octahe-dral (O 2Àocta :)oxygen interstitial are found to be the lowest-energy configurations within a certain Fermi energy range.In both oxides,the O 0split is the most mobile,and the migration energies of the split oxygen interstitials in ThO 2are lower than in CeO 2,indicating higher oxygen interstitial mobility in ThO 2than in CeO 2.Ó2013Acta Materialia Inc.Published by Elsevier Ltd.All rights reserved.Keywords:DFT;Charged defect;Oxygen interstitial;Stability and migration1.IntroductionFluorite-structured oxides such as UO 2,PuO 2and ThO 2are important nuclear fuels in fission reactors [1,2],where they are exposed to irradiation damage from neutrons,high-energy charged particles (e.g.fission products)and alpha decay.Such irradiation damage produces atomic point defects,as well as electrons and holes that can trap point defects.The point defects contribute to the micro-structural evolution in nuclear fuel,although many of these defects recombine directly at elevated temperatures [3].The mobility of these primary radiation defects plays an impor-tant role in the microstructural evolution,and secondary diffusion-controlled reactions between defects can result in the formation of defect clusters,dislocation loops and voids.For example,the so-called Willis cluster that is formed by oxygen interstitial aggregation has been observed in UO 2experimentally [4].Oxygen interstitial dis-location loops lying on the {111}plane have been observed by Yasunaga et al.[5]in CeO 2irradiated withan electron beam.The formation of such defects may ulti-mately lead to the degradation of thermal and mechanical properties of nuclear materials [6].In addition to nuclear applications,oxygen interstitial defects have been sug-gested to provide oxygen mobility that facilitates the oxy-gen storage capacity of CeO 2in catalytic converters [3,7].Also,in systems such as ThO 2+x ,the anion-to-cation ratio has a strong effect on the physical and chemical properties,e.g.thermal conductivity [8].Understanding the stability and migration of oxygen interstitials is thus of critical importance for the evaluation of material properties and performance.In the past few decades,extensive studies of oxygen interstitial formation and transport in UO 2have been car-ried out [1,9–13].ThO 2and CeO 2,on the other hand,have received relatively less attention [1,14,15].In these studies,the point defects were treated as neutral charge states.However,it is well known that point defects in semicon-ductors and ceramics may be electrically charged due to doping,impurities or nonstoichiometry.For example,the oxygen interstitial in PuO 2.25is found to be singly charged (O À)[16].Under irradiation,atomic defects are produced by displaced atoms and even greater numbers of electrons1359-6454/$36.00Ó2013Acta Materialia Inc.Published by Elsevier Ltd.All rights reserved./10.1016/j.actamat.2013.09.001⇑Corresponding author.E-mail address:hyxiao@ (H.Y.Xiao)./locate/actamatAvailable online at ScienceDirectActa Materialia 61(2013)7639–7645and holes are created by ionization.Thus,even if neutral defects are created under irradiation,the trapping of ioni-zation-induced electrons and holes can result in the forma-tion of charged defects,as in the case of yttria-stablized ZrO2[17].These charged defects can affect defect structure, trapping rates of electrons and holes,defect formation and migration energies[18],and the kinetics of microstructure evolution,as in the faster grain growth observed in nano-crystalline cubic ZrO2under irradiation at cryogenic tem-peratures compared to higher temperatures[19].In the case of ZnO,it has been shown that the diffusion mecha-nism for the oxygen interstitial is dependent on the defect charge state[20].Other important properties,such as the luminescence quenching rates,may also be influenced by the charge state.Recently,the charge states of defects influorite-struc-tured oxides have gained increasing interest[21–24],but these studies are mainly focused on the formation of charged defects.At present,the stability and migration of charged oxygen interstitials influorite-structured oxides, including the migration energies and pathways,has not yet been well studied.In this study,we investigate charged oxygen interstitial formation and migration in ThO2and CeO2.Here,CeO2is used as a surrogate material in place of PuO2for performance evaluation in harsh environments [25–27],because they share the same crystallographic struc-ture,and several thermophysical and chemical properties. Our main aims are:(i)to gain fundamental insight into charged oxygen interstitial behavior in ThO2and CeO2; (ii)to motivate experimental studies and provide support for their interpretation;and(iii)to provide physical param-eters(e.g.defect configurations and energetics)for higher-scale modeling offluorite-structured oxide fuels.putational detailsAll the calculations were carried out within the density functional theory(DFT)framework using the projector-augmented wave method,as implemented in the Vienna Ab Initio Simulation Package(VASP)[28].The exchange-correlation effects were treated by the local-den-sity approximation(LDA)in the Ceperley–Alder parame-trization[29],with spin-polarized effects considered. Structural optimizations were carried out at variable cell shape and volume,as well as under the condition that the Hellmann–Feynman force on each atom should be smaller than0.01eV A˚putations were based on a2Â2Â2 supercell consisting of96atoms,with a4Â4Â4k-point sampling in reciprocal space and a cutoffenergy of 550eV for the plane-wave basis set.Our previous work on oxygen vacancy formation and migration in CeO2has shown that the Hubbard U correction for the on-site Cou-lomb interaction must be taken into account due to the existence of Ce3+[30],which is consistent with other theo-retical studies on reduced ceria[31–33].In this study,plus U correction calculations were also performed to investi-gate if the Hubbard U correction for Th5f(or Ce4f)electrons is necessary for ThO2(or CeO2)containing anoxygen interstitial.In the LDA+U calculations,the method proposed by Dudarev et al.[34]was used,and effective U values of4eV for Th and6eV for Ce,obtained from our previous study[30],were employed.The mini-mum-energy pathways for oxygen interstitial migration in ThO2and CeO2were investigated by the climbing-image nudged elastic band method[35].3.BackgroundFor systems with charged defects,spurious electrostatic and elastic interactions between the defect and its periodic images can be large,and the system converges very slowly with respect to the supercell size.To correct the electro-static effects on the formation energies of charged defects, several approaches have been proposed[36–40].Here,the screened Madelung-like lattice energy of point defects pro-posed by Leslie and Gillan[39]is employed,i.e.E corr¼q2a M2e L, where L=XÀ1/3is the linear supercell dimension,X is the volume of the supercell,e is the dielectric constant and a M is the appropriate Madelung constant for the respective supercell geometry.Another correction for the charged sys-tem is the potential alignment,D V,which is used to esti-mate the valence band maximum(VBM)of the defective supercell.The D V value is obtained by the averaged differ-ence between the local potentials far from the defect in the defective supercell and the corresponding ones in the per-fect supercell[41].The defect formation energies are definedby E f¼E defÀE perfectþn i l Oþq E FþE bulkVBMþD VÀÁþE corr [42],where E def and E perfect are the total energies of the supercell with and without a defect,respectively,n i is the number of atoms being removed or added,and l O is the chemical potential of O.The value of l O is obtained under O-rich or M-rich(M=Th or Ce)conditions.Under O-rich conditions,the experimental chemical potential of O(l O) from the free O2molecule is employed[43];under M-rich conditions,l O is obtained by l MO2¼l Mþ2l O;wherelMO2and l M are calculated from the total energies of bulk MO2and M,respectively.The term in parentheses is the electronic chemical potential that represents the change in energy associated with charged defects.In this term,E F is the Fermi level in the bulk with reference to the VBM,which can vary within the band gap,E bulkVBMis the energy of the bulk VBM,and D V is the electrostatic potential alignment of the defective structure.The additional charge q is set by adding or removing electrons from the supercell. The last term,E corr,is thefirst-order Madelung correction energy.4.Results and discussionparison of LDA+U and LDA calculations for oxygen interstitial formationPulsed neutron diffraction experiments performed on a nanoscale powder of CeO2by Mamontov and Egami7640H.Y.Xiao et al./Acta Materialia61(2013)7639–7645revealed oxygen interstitial occupation at the octahedral site of the CeO2[3].Our ab initio molecular dynamics sim-ulation of low-energy recoil events in ThO2,CeO2and ZrO2also showed that,under low-energy irradiation,oxy-gen interstitials generally occupy the octahedral site(O octa.)[2].In addition to this octahedral site,the O–O h110i split interstitial(O split)is also a possible stable defect.These two oxygen interstitial(O int)configurations,as shown in Fig.1, are considered as the initial configurations in the present work to study charged oxygen interstitial incorporation and migration in ThO2and CeO2.To investigate the effect of considering the Hubbard U correction for Th5f and Ce4f electrons on the stability of oxygen interstitial in ThO2and CeO2,the formation energies for the octahedral oxygen interstitials with charge states varying from2Àto2+arefirst calculated by both LDA and LDA+U methods.The variation of the formation energies as a function of the Fermi level with different charge states in both oxides is shown in Fig.2. Under both O-rich and Th-rich conditions,it appears that consideration of the Hubbard U correction for the Th5f electrons has only a small influence on the interstitial formation energies in ThO2.In CeO2,the plus U correctionfor the Ce4f electrons affects the O2Àocta:interstitialformation under both O-and Ce-rich conditions,which narrows the stability region by$0.25eV.The density ofstate distribution for the O2Àocta:interstitial in CeO2andThO2obtained by both methods is further analyzed,as illustrated in Fig.3.It turns out that the standard LDA describes well the splitting of Ce4f and Th5f electrons into occupied and unoccupied states,and LDA+U only pushes the unoccupied states to a higher energy level.This is different from the case of oxygen vacancy formation in CeO2[30],for which the Hubbard U correction for the on-site Coulomb interaction is necessary to localize the Ce4f electrons.For the split oxygen interstitials in both oxides,the LDA+U and LDA methods also predict very similar formation energies,and the f electrons are well 4.2.Stability of oxygen interstitialsThe defect formation energies for octahedral and splitoxygen interstitials in ThO2and CeO2are presented in Fig.4a and b,respectively.Because oxygen interstitials are more favorable under O-rich conditions than Th-rich conditions,only the O-rich condition is considered here. In ThO2,it is found that the Oþsplit,O0split,OÀocta:and O2Àocta: are the lowest-energy configurations in the Fermi energy ranges0–0.32,0.32–1.35, 1.35–2.73and 2.73–4.04eV, respectively.The geometrical configurations for the Oþsplit,O0splitand O2Àocta:interstitials in ThO2are shown in Fig.5. Our calculations indicate that the stability of oxygen inter-stitial depends on the charge state,Fermi level and oxygen interstitial configuration.The stability of oxygen interstitial in ThO2is found to be different from that in UO2 [21,22,44],for which the O2-interstitial is more stable over most of the Fermi energy range.Such a discrepancy may be caused by the different interactions between the oxygen interstitial and its neighbors.In CeO2,the Oþsplit,O0splitand O2Àocta:interstitials are the low-est-energy configurations in the Fermi energy ranges0–0.39, 0.39–1.76and 1.76–2.17eV,respectively,as shown inFig.4b.Similar to the case of ThO2,the Oþsplitinterstitial is preferred under p-type conditions,where the Fermi level isvery close to the valence band maximum,and O2Àocta:is favored under n-type conditions,i.e.as the Fermi level approaches the conduction band minimum.These results suggest that,in both ThO2and CeO2,the oxygen interstitial is likely to lose electrons under p-type conditions and gain electrons under n-type conditions,behaving as a donor and acceptor defect,respectively.Erhart et al.[45]also sug-gested the donor-and acceptor-like characters of the oxygen interstitial atoms in ZnO.It should be pointed out that the singly positive split interstitials are only stable when the Fermi level is very close to the valence band maximum.Bad-er charge analysis shows that these singly positive split inter-stitials donate electrons to all of theirfirst-neighboring cations,resulting in a positive charge state of the interstitials. Anotherfinding is that the energy difference between the octahedral and split interstitials with a specific charge stateis much smaller in ThO2,and that OÀocta:is one of the low-est-energy configurations within the Fermi energy range in ThO2but not in CeO2.This suggests despite the fact that ThO2and CeO2have the samefluorite-type structure,the size and electronic configuration of the cations may signifi-cantly affect the oxygen interstitial stability.To study the effect of charge states on the interatomic structures,the structural properties for oxygen interstitials with different charge states in both oxides have been further analyzed,as summarized in Table1.For the octahedral interstitials,the distance between the oxygen interstitial and its neighboring lattice oxygens increases as q increases from2Àto2+.This is because in MO2the lattice O ions are negatively charged,and the introduction of negatively or positively charged O int will push the nearest lattice oxygens away due to the repulsive interaction,or pull theFig.1.Schematic view of(a)octahedral(O octa.)and(b)split(O splitoxygen interstitial in ThO2.H.Y.Xiao et al./Acta Materialia61(2013)7639–76457641of oxygen interstitial formation energies with Fermi level in(a and b)ThO2and(c and d)CeO2under O-and M-rich and dotted lines correspond to the results obtained from LDA+U and LDA calculations,respectively.Density of state for O2Àocta:interstitial in(a)CeO2and(b)ThO2by LDA and LDA+U calculations.The Fermi level is set at the the energy.Fig.4.Oxygen interstitial formation energies as a function of the energy in(a)ThO2and(b)CeO2.Solid and dashed lines octahedral and split interstitials,respectively.nearest lattice oxygens closer due to the attractive interac-tion,respectively.Consequently,positive oxygen intersti-tials cause volume compression,and neutral or negative oxygen interstitials cause volume expansion.In the case of split interstitials,the h O int –O int i distance increases as q varies from 2+to 2À;however,the distances between either O int of the split interstitials and their neighboring lat-tice oxygens do not exhibit a singular change.Further-more,the introduction of the O 2þsplit into the system causes volume compression,and the split interstitials with other charge states cause volume swelling.Obviously,the charge states have considerable effects on the geometrical struc-tures for both split and octahedral interstitials.For some split interstitials in ThO 2and CeO 2,it is noted that the h O int –O int i bond distance is close to that of a freeO 2molecule,i.e.1.21A˚.However,the O–O split interstitial interacts with its neighboring atoms,and does not form an O 2molecule.Fig.6shows the charge density distribution for the O þsplit interstitial in ThO 2.The h Th–O 1i and h Th–O 2i bond lengths are each 2.46A˚.Each O int in the split interstitial interacts with two lattice oxygens at bond dis-tances of 2.41and 3.38A˚,respectively.The average Bader charge of the two oxygens in the split interstitial is +0.58|e|,as compared with the charge of ±0.16|e|in a free O 2,suggesting that the two oxygens in the split interstitial do not form a free molecule.Our theoretical prediction of the structural and electronic properties of the O þsplit pro-vides fundamental information for the design and interpre-tation of planned low-temperature irradiation experiments in these fluorite-structured oxides.(a) O split +(b) O split 0(c) O octa.2-<O-O>:1.39 Å<O-O>:1.43 ÅFig.5.Schematic view of geometrical configuration for (a)O þsplit ,(b)O 0split and (c)O 2Àocta :in ThO Table 1Geometrical properties for oxygen interstitial in ThO 2and CeO 2:d h O int –O int i is the h O–O i bond length of the split interstitial;d h O int –O lat i is the distance between the interstitial and its neighboring lattice oxygens;and D V is the defect formation volume relative to the perfect volume (V 0).ThO 2CeO 2d h O int –O int i (A˚)d h O int –O lat i (A ˚)D V /V 0(%)d h O int –O int i (A ˚)d h O int –O lat i (A ˚)D V /V 0(%)O 2þsplit1.362.38À0.28 1.31 2.28À0.41O þsplit 1.38 2.410.22 1.35 2.350.20O 0split 1.43 2.470.74 1.39 2.410.93O Àsplit1.992.43 1.24 1.40 2.42 1.78O 2Àsplit 2.43 2.42 1.76 2.35 2.35 2.23O 2þocta :– 2.44À0.90– 2.36À1.12O þocta :– 2.45À0.39– 2.37À0.46O 0octa :– 2.470.14– 2.400.23O Àocta :– 2.510.69– 2.430.98O 2Àocta :–2.541.26–2.471.87ThO 1O 2O(a)O 1O 2Th(b)2.46 Å2.46 Å1.38 Å(c)O 1O 2O 2.41 Å3.38Å2.41 ÅO O split +O split +O split +distribution for O þsplit in ThO 2projected on planes (a)containing interstitials and their first neighboring their first neighboring cations and (c)containing interstitials and their first neighboring anions.H.Y.Xiao et al./Acta Materialia 61(2013)7639–764576434.3.Oxygen interstitial migrationThe calculated energy barriers for oxygen interstitial migration in ThO 2and CeO 2are given in Table 2.In both oxides,the O þsplit is the most mobile,with migration energies of 0.13and 0.56eV in ThO 2and CeO 2,respectively.The O 0split interstitials,which also have a high degree of stability,have only slightly higher migration energies.These results indicate that the oxygen split interstitial is more mobile in ThO 2than in CeO 2.The activation energy for oxygen self-diffusion in ThO 2,which occurs via oxygen vacancies,has been determined experimentally [1,14];however,direct experimental measurement of oxygen vacancy and intersti-tial migration energies have not been reported.As shown in Fig.7,the saddle-point for O þsplit migration corresponds to the oxygen interstitial occupying an octahe-dral site O þocta :ÀÁ,which was shown to be a metastable state in Fig.4.The distance between the O int and its neighboringTh atoms is 2.79A˚,which is 0.33A ˚larger than that in the migrating defect replaces one lattice atom,and the lattice atom then becomes the migrating species,have been con-sidered [46,48].Although different migration barrier values were obtained,these calculations suggested that the inter-stitialcy mechanism in UO 2is more energetically preferable than the direct interstitial mechanism.For ThO 2and CeO 2,the interstitialcy mechanism is also found to be more favor-able than the direct interstitial mechanism.The case of O 2Àocta :interstitial migration in ThO 2via the interstitialcy mechanism is illustrated in Fig.7,where the saddle-pointcorresponds to the O 2Àsplit configuration.However,the energy barrier is significantly higher than that for O þsplit interstitial migration.Our calculations suggest that oxygen interstitial migra-tion in ThO 2and CeO 2is influenced by the charge state,configuration of the oxygen interstitial,and the composi-tion of host material.In ZnO,Erhart and Albe [20]also found the O 2-interstitial migrates via a different mecha-nism than the O 0and O 2+interstitials.The fact that the migration barrier and pathway are strongly dependent on the charge state in some oxides suggests the possibility of using an applied electric field to affect the diffusion and to control defect concentrations [48].The migration behav-ior of the oxygen interstitial in ThO 2and CeO 2generally exhibit similar characteristics,whereas the size and elec-tronic configuration of the cations still influence the migra-tion barriers,resulting in lower oxygen interstitial mobility in CeO 2.It is expected that these results may provide some new insights for future theoretical and experimental studies of point defects behavior in fluorite-structured oxides.5.ConclusionsIn summary,an ab initio method based on DFT has been employed to study the stability and migration of charged oxygen interstitial in ThO 2and CeO 2.It is shown that the Fermi level has a significant influence on the stabil-ity of oxygen interstitial.In ThO 2,the O þsplit ,O 0split ,O Àocta :and O 2Àocta :are the lowest-energy configurations in the Fermi energy ranges 0–0.32,0.32–1.35, 1.35–2.73and 2.73–4.04eV,respectively.In the case of CeO 2,the O þsplit ,O 0splitand O 2Àocta :interstitials are the lowest-energy configurations in the Fermi energy ranges 0–0.39,0.39–1.76and 1.76–2.17eV,respectively.These results suggest that oxygen interstitials behave as donor-and acceptor-like defects under p -type and n -type conditions,respectively.Split and octahedral interstitials with different charge states can cause local volume compression or swelling.Although the h O–O i bond length of split interstitial is close to that of a free O 2,the two oxygens interact with their neighbors rather than forming a free O 2molecule.In both oxides,the O þsplit migration has the lowest migra-tion barrier,for which the saddle-point corresponds to the oxygen interstitial occupying an octahedral site.The lowest migration energies are determined to be 0.13eV in ThO 2and 0.56eV in CeO 2,indicative of a higher mobility for the oxygen interstitial in ThO 2.Our calculations suggestTable 2Energy barrier for oxygen interstitial migration in ThO 2and CeO 2.ThO 2CeO 2O þsplit 0.130.56O 0split 0.320.76O Àocta :0.98–O 2Àocta :1.040.80Fig.7.Migration pathway for O 0split and O 2Àocta :in ThO 2.7644H.Y.Xiao et al./Acta Materialia 61(2013)7639–7645that the oxygen interstitial behavior in ThO2and CeO2is influenced by the charge state,interstitial configuration and composition of the host material.The stability and migration of the oxygen interstitial in both oxides generally exhibit similar characteristics;however,the migration bar-riers are significantly affected by cation size and electronic configuration.AcknowledgementsThis work was supported as part of the Materials Sci-ence of Actinides,an Energy Frontier Research Center funded by the US Department of Energy,Office of Science, Office of Basic Energy Sciences.The theoretical calcula-tions were performed using the supercomputer resources at the Environmental Molecular Sciences Laboratory lo-cated at Pacific Northwest National Laboratory,and the National Energy Research Scientific Computing Center lo-cated at Lawrence Berkeley National Laboratory. 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Advanced Structural Analysis
Advanced Structural Analysis Advanced Structural Analysis is a field that plays a crucial role in thedesign and construction of various structures, ranging from buildings to bridges.It involves the application of mathematical principles and engineering concepts to analyze the behavior and performance of these structures under different loading conditions. This analysis helps engineers ensure the safety, stability, and durability of the structures, while also optimizing their design and cost-effectiveness. One perspective to consider in advanced structural analysis is the technical aspect. Engineers use sophisticated software and computational tools to model and simulate the behavior of structures. They apply principles of mechanics, such as equilibrium, compatibility, and constitutive relationships, to determine the internal forces and deformations within the structure. By analyzing these results, engineers can assess the structural integrity and identify potential weaknesses or areas of improvement. This technical perspective requires a deep understanding of structural mechanics, numerical methods, and computational tools. Another perspective to consider is the economic aspect. Advanced structural analysis helps engineers optimize the design of structures to minimize material usage and construction costs, while still meeting safety and performance requirements. By accurately predicting the behavior of a structure, engineers can make informed decisions about the selection of materials, dimensions, and construction techniques. This can result in significant cost savings during the construction phase, as well as in the long-term maintenance and operation of the structure. The economic perspective is crucial in ensuring that structures are not only safe and functional but also financially viable. From a safety perspective, advanced structural analysis plays a vital role in ensuring the integrity and stability of structures. By analyzing the response of a structure to different loading conditions, engineers can identify potential failure modes and take appropriate measures to prevent catastrophic failures. This includes considering factors such as wind loads, earthquakes, and dynamic effects. By conducting advanced structural analysis, engineers can design structures that can withstand these external forces and provide a safe environment for occupants. Furthermore, advanced structural analysis also considers the sustainability aspect. Engineersaim to design structures that have minimal environmental impact throughout their lifecycle. This includes using sustainable materials, optimizing energy efficiency, and considering the long-term durability and recyclability of the structure. By incorporating these considerations into the analysis, engineers can contribute to the overall sustainability goals of a project and reduce the environmentalfootprint of structures. Lastly, it is important to consider the societal perspective. Advanced structural analysis ensures that structures are not onlysafe and economically viable but also meet the needs and expectations of society. This includes considering factors such as aesthetics, functionality, and cultural significance. By analyzing the behavior of structures, engineers can make informed decisions about the design and construction methods that align with societalvalues and preferences. This perspective emphasizes the importance of designing structures that are not only technically sound but also socially accepted and appreciated. In conclusion, advanced structural analysis encompasses various perspectives that are essential for the design and construction of safe, cost-effective, sustainable, and socially accepted structures. The technical aspect involves applying mathematical principles and computational tools to analyze the behavior of structures. The economic aspect focuses on optimizing the design to minimize costs while meeting safety requirements. The safety perspective ensures the integrity and stability of structures under different loading conditions. The sustainability aspect considers the environmental impact throughout the lifecycle of the structure. Lastly, the societal perspective emphasizes the importance of designing structures that align with societal values and preferences. By considering these multiple perspectives, engineers can ensure that structures not only serve their functional purpose but also contribute to the well-being and satisfaction of society.。
铸造英文词汇自己总结
铸造词汇abrasion磨损abrasion resistance耐磨性abrasion resistant耐磨的abrasive blasting喷丸处理abreuvage机械粘砂acceptance验收accuracy精度accuracy of manufacture制造精度acicular iron贝氏体铸铁acid refractories酸性耐火材料acierage渗碳agglomerate烧结aging时效air cooling空冷air harden空气硬化并回火air quenching正火alloy steel castings合金钢铸件alloy constituent合金成分ambient temperature室温annealing退火arc furnace电弧炉artificial aging人工时效asperities粗糙度assemble and close the mold合箱atmospheric feeder大气压力冒口attrition磨损austenite奥氏体bainite贝氏体bakelite resin酚醛树脂baking烘烤base iron原生铁basic 碱性的baume玻美度bench molding台上造型binary alloy二元合金black steel碳钢blast cleaning喷丸处理blind feeder暗冒口blow砂眼blowhole气孔bluing发蓝boron硼bottom gate底注式浇口box-type furnace箱式炉brittle脆的brittle fracture脆性断裂bull ladle大浇包，铁水包burned-in-sand粘砂burr毛刺burring去毛刺calibration校准carbon碳carbon steel碳钢carburization渗碳chaplet芯撑cheek中间箱chromium铬chromium steel铬钢chromizing镀铬cold fracture/rupture冷裂cold setting冷硬的，自硬的cold setting resin binder自硬树脂粘结剂cold-shortness低温脆性cold work冷加工collapsibility溃散性columnar grain柱状晶columnar structure柱状组织combustion燃烧commercial foundry专业铸造厂compactibility紧实性component成分composition成分compressed air压缩空气compression strength抗压强度condense冷凝connor gate缝隙浇口consistency浓度constituent组成continuous连续的chill冷铁cope上箱drag下箱core芯core bar芯骨core blacking型芯涂料core box芯盒core sand芯砂cost成本cover flux覆盖剂crack裂纹crack impregnation test裂纹渗透试验crane起重机critical temperature临界温度cross gate横浇口cross-joint of casting错箱crush破碎，压碎crystal晶体crystalline结晶的cure处理dead annealing完全退火deairing排气deburr去除毛刺飞边deflocculation弥散deformation变形degas除气degasification除气处理degasfier除气剂degree of moistening湿度degree of purity纯度density密度deoxidation脱氧dephosphorize脱磷derust除锈desunfurization脱硫diameter直径dimension尺寸inspection检查tolerance公差dissolve溶解distortion变形double tempering二次回火downsprue/downgate直浇口draw表面缩松dress上涂料，清理dross铁渣ductile iron球铁ductility延伸性durability持久性，耐久性dye penatrant染色剂economic efficiency经济性elastic deformation弹性变形electric welding电弧焊electromagnetic电磁的agitation搅拌electroplating电镀elongation延伸率embrittlement脆裂endurance limit疲劳极限EPC消失模铸件equlibrium diagram铁碳相图equipment装置ester-cured/phenolic nobake碱性酚醛树脂eutectic arrest共晶转变eutectoid reaction共析转变eutectoid steel共析钢exhaust排气exothermic feeder发热冒口fabrication制造，加工fatigue fracture疲劳断裂feed metal补缩液feed modulus冒口模数ferrite铁素体matrix基体fettle修补，清炉渣fettling shop清理车间filler sand背砂finish精加工，抛光finish allowance加工余量finish mark加工符号finished machine drawing铸件工艺图，机械加工图finished product成品fire cracking退火裂纹fluidity流动性foundry industry铸造业foundry practice铸造生产freezing凝固friable脆的furan resin呋喃树脂furnace cover炉盖galvanize电镀，镀锌gaseous气体的ingate内浇口gating and feeding system浇冒系统grain refinement晶粒细化graphite石墨gravity die casting金属型铸造hammer榔头hardenability淬透性hardening furnace淬火炉hardness penetration depth淬硬深度heat up升温heat check热裂solution固溶处理velocity速率heredity遗传性high grade steel优质钢holding temperature保温温度homogenizing扩散退火hot brittleness热脆性hot crack热裂hot permeability高温透气性tensile strength抗拉强度hydrogen氢hypereutectoid过共析的hypoeutectoid亚共析的immersion hardening液体淬火impregnate浸透impression压痕impurity杂质inclusion夹渣indicate显示induction感应induction hardening感应淬火inert gas惰性气体infrared红外的infusible难熔的ingot钢锭injection注入inoculation孕育insulated feeder保温冒口inversion casting翻箱铸造investing熔模铸造iron-carbon phase diagram铁碳相图isothermal等温的joint surface/face分型面joint flash披缝kiss gate压边冒口knock-off riser core易割冒口片knockout开箱knockout core抽芯laboratory实验室lacquering涂漆ladle浇包ledeburite莱氏体line frequency工频line frequency induction furnace工频感应电炉liquid carburizing液体渗碳live riser热冒口longitudinal crack纵向裂纹loose piece活块low alloy steel低合金钢aluminium铝mangenese猛phosphorus磷lubricate润滑machcrocavity宏观缩孔magnetic particle testing磁力探伤manganese steel锰钢manganiferous含锰的martensite马氏体mean stress平均应力measurable可测量的mechanical property机械性能medium frequency induction funace中频感应电炉metal penetration机械粘砂metallographic exam金相检验mismatch in mould错箱misrun浇不满modification变质处理moldability成型性molybdenum钼mottled cast iron麻口铁mold wash铸型涂料multiple gate多浇口系统natural aging自然时效nickel镍nickel-chromium alloy镍铬合金nitride氮化nobake binder自硬砂粘结剂normalizing正火nowel下箱oil quench油淬operating instruction操作规程operating method操作方法osmosis渗透osmotic渗透的oxygen氧oxygen content含氧量partial aging部分时效parting agent/compound脱模剂pattern draft/taper拔模斜度patternmaker’s ruler/shirinkage缩尺phenolic resin酚醛树脂phenolic sand molding树脂砂造型pour浇注pressure riser/feeder压力冒口primary austenite初生奥氏体pumping压力补缩quality certificate质量合格证quench aging淬火时效ram舂砂rare earth稀土raw casting未经清理的铸件recarburizer增碳剂recovery/reclaim再生，回收reduce还原reducing melting还原熔炼reducing treatment还原处理reduction of area断面收缩refine精炼refiner精炼剂refractory耐火材料refuse废品refuse removal废品消除regulable可调节的reinforce加固，加强release agent脱模剂relieve stress消除应力remedial action补救措施residual残留物，剩余的return sand回用砂，旧砂reversible可逆的riser base冒口窝riser gating冒口浇注rockwell hardness洛氏硬度roll over翻箱rough粗糙的runner浇道rupture断裂rust prevention防锈作用rustproof coating防锈涂料salt bath hardening盐浴淬火sample试样，样品sampling取样sand binder型砂粘结剂sand compaction型砂紧实度sand inclusion夹砂scabing夹砂scale氧化皮scrap steel废钢scum浮渣segregate偏析self-curing binder自硬化粘结剂shake out打箱，落砂short run浇不足shrinkage vavity缩孔shrinkage hole缩孔shrinkage porosity缩松silicon硅slag炉渣，夹渣smelt熔炼smoothness光洁度snag粗加工，打磨solidification凝固作用solidify凝固solution heat treatment固溶处理sorbite索氏体special steel特种钢spectra analysis/spectrography光谱分析sprue浇口sprue base直浇道窝stationary固定不动的steadite磷共晶steel scrap废钢strain过滤，应变stress crack应力裂纹stress relief anneal消除应力退火structural constiuent组织成分supercooled过冷的surface defect表面缺陷tap出钢temper回火tempered martensite回火马氏体tensile test拉伸试验test block试块toughness刚度，韧性trace微量元素transformation转变，相变undercooling过冷velocity速度vibrate振动wear resistance耐磨性yield产量。
中南大学学术交流英语-试题构成与翻译题库
一.阅读理解(50%)Section Aa.会议通知(Call for Papers) T/F 10%b.文献T/F 10%Section Bc.文献排序15%Section Cd.文献简答题15%二.翻译(30%)Section Aa.英译汉15%Section Bb.汉译英15%三.学术英语写作20%Case 1: 开幕词P139, P141Case 2: 闭幕词P143 (E1-book)Case 3: 投稿信P75 (E2-book): 附上论文的标题; 介绍研究方法(假设)(1-2句); 介绍研究结果(3-4句); 研究的意义与价值; we believe…; 日期.Case 4: 回函P86 E2-book.附录A 英译汉,汉译英题目1. P5A helpful image is to think about submitting a manuscript to an international journal as a way of participating in the international scientific community. You are, in effect, joining an international conversation. To join this conversation, you need to know what has already been said by the other people conversing. In other words, you need to understand the cutting edge of your scientific discipline: what work is being done now by the important players in the field internationally. This means:向国际学术杂志投稿有助于进入国际学术界，事实上你加入了国际间的交流。
IEC61400-1-2005风电机组设计要求标准英汉对照
需要什么文档直接在我的文档里搜索比直接在网站大海捞针要容易的多也准确省时的多
INTERNATIONAL STANrbines – Part 1:
Design requirements
Publication numbering As from 1 January 1997 all IEC publications are issued with a designation in the 60000 series. For example, IEC 34-1 is now referred to as IEC 60034-1.
Further information on IEC publications The technical content of IEC publications is kept under constant review by the IEC, thus ensuring that the content reflects current technology. Information relating to this publication, including its validity, is available in the IEC Catalogue of publications (see below) in addition to new editions, amendments and corrigenda. Information on the subjects under consideration and work in progress undertaken by the technical committee which has prepared this publication, as well as the list of publications issued,is also available from the following: IEC Web Site (www.iec.ch) Catalogue of IEC publications The on-line catalogue on the IEC web site (www.iec.ch/searchpub) enables you to search by a variety of criteria including text searches,technical committees and date of publication. Online information is also available on recently issued publications, withdrawn and replaced publications, as well as corrigenda. IEC Just Published This summary of recently issued publications (www.iec.ch/online_news/justpub) is also available by email. Please contact the Customer Service Centre (see below) for further information. Customer Service Centre If you have any questions regarding this publication or need further assistance, please contact the Customer Service Centre: Email: custserv@iec.ch Tel: +41 22 919 02 11 Fax: +41 22 919 03 00 .
[整理]-12-英文文章大肠杆菌感染.
β-glucan and E. coli infectionIntroductionEscherichia coli is commonly found in the avian gastrointestinal tract and other mucosal surfaces. Although most of the strains are commensals, a separate group, designated avian pathogenic E. coli, has the ability to cause extraintestinal disease in poultry, collectively called colibacillosis (Kariyawasam et al., 2006; Bonnet et al., 2009). Serotypes O1, O2, and O78, and to some extent O15 and O55, are the most common serotypes associated with colibacillosis found in chickens (Gomis et al., 1997; Raji et al., 2007). They commonly cause airsacculitis, pericarditis, perihepatitis, peritonitis, salpingitis, and subsequently the most acute form, septicemia, resulting in sudden death (Mellata et al., 2003; Ask et al., 2006). The poultry industries worldwide suffer great financial losses every year because of the high morbidity and mortality rates caused by colibacillosis. Treatment strategies include the control of environmental factors and the use of antibiotics. However, concerns exist regarding the emergence of antibiotic resistance of normal microflora and pathogenic bacteria, which may in turn threaten human health through transfer f drug resistance genes to zoonotic bacteria (Food and griculture Organization of the United Nations, World ealth Organization, and World Organization for Animal ealth, 2003).Avian colibacillosis, a disease caused by a group of bacteria called avian pathogenic Escherichia coli (APEC) in chickens, turkeys, and other avian species, is an infectious disease that often causes severe mortality and subsequently results in economic losses to the poultry industry ( Gibbs et al., 2004). The disease is associated with a complete set of syndromes including septicemia, airsaculitis, pericarditis, and swollen head syndrome (Chevilleand Arp, 1978; Rodriguez-Siek et al., 2005). Several E.coli isolates are commonly associated with colibacillosisin poultry, and the serogroups O1, O2, and O78 have been recognized as the predominant sources involved in this disease (Whittam and Wilson, 1988; McPeake et al., 2005). A high raA high rate of antibiotic resistance was observed while testing these serogroups, which probably originates from the extensive use of antibiotics in the poultry industry (Allan et al., 1993), as well as by acquisition of R plasmids (Johnson et al., 2005b; Skyberg et al., 2006). Numerous concerns about the use of antibiotics in the poultry industry have been raised including the further selection of drug-resistant strains (Franklin, 1999; Angulo et al., 2004). There are also human health issues involved due to the potential transfer of E. coli from animals via the food chain (Angulo et al., 2004; Johnson et al., 2005a). This has attracted considerable attention from researchers who are seeking alternatives for control and treatment of colibacillosis in animals.One promising alternative to antibiotics is the use of virulent bacteriophage against E. coli serogroups O1, O2, and O78, a well-established approach that phages for these serogroupsare able to be isolated and used in phage therapy against bacterial cells. Bacteriophages are a class of viruses that live and replicate in bacteria (Ackermann, 2000) and have the ability to attack a single species or subset of a species of bacterium, making them potential antibacterial agents.β-Glucans have been well studied in human and animal subjects, and their immune-enhancing effects have been well noted (Volman et al., 2008). Due to their ability to augment the immune response, β-glucans have been termed biological response modifiers. β-Glucans are structural components of the cell wall of many bacteria, fungi, and yeast, as well as cereal grains such as oat and barley. β-Glucans from fungal and yeast sources have been widely studied and shown to be most effective in enhancing protective immunity against infectious agents (Soltanian et al., 2009).Though the immune-enhancing capabilities of β-glucans have been proven in mammals, limited reported research is available for poultry, with mixed results in terms of performance and immune response. Some studies have shown that β-glucan supplementation improves BW (Zhang et al., 2008), whereas other groups have found no significant effects (Chae et al., 2006). Huff et al. (2006) reported contradictory results in which β-glucan supplementation was detrimental to BW in a nonchallenge setting but was found to be beneficial during an Escherichia coli challenge. These varying results indicate that more research needs to be carried out to determine the optimal dosage and proper usage of β-glucans to obtain consistent results. β-Glucans have beneficial effects on both the innate and adaptive immune systems. When exposed to β-glucans in vitro, chicken macrophages and splenocytes have been shown to experience enhanced proliferation and improved phagocytic capabilities (Chen et al., 2003; Guo et al., 2003). In terms of the adaptive immune response, β-glucans magnify plasma IgG and IgA levels, indicating an upregulation of the humoral immune response (Zhang et al., 2008). The T-lymphocyte subpopulations are also affected, with higher CD4+, CD8+, and CD4+:CD8+ T-cell populations found in chickens supplemented with β-glucan (Chen et al., 2003; Chae et al., 2006). Furthermore, β-glucans have demonstrated the ability to augment the secretion of several cytokines to aid in pathogen elimination. Macrophages isolated from birds fed β-glucans demonstrated enhanced interleukin (IL)-1 (Guo et al., 2003), IL-2, and interferon (IFN)-γ levels (Zhang et al., 2008). Dietary β-glucan has also been shown to increase the size of the primary and secondary lymphoid organs, providing further evidence of their immunomodulating capabilities (Guo et al., 2003; Zhang et al., 2008).Materials and methodsExperimental Animals and TreatmentsA 3-wk experiment was conducted to determine the efficacy of bacteriophage EC1 in treating respiratory infection in birds caused by E. coli O78:K80. A total of 480 one-day-old male broiler chicks (Ross 308) were obtained from a commercial hatchery. The chicks were assigned randomly to 4 treatment groups, each with 4 pens of 30 chicks per pen. Water and broiler feed (antibiotic free) were provided ad libitum throughout the experimental period. The 4 treatment groups were group I (control), in which untreated, unchallenged birds were administered 0.2 mL of PBS only (0.14 M NaCl, 0.0027 M KCl, 0.01 M Na2HPO4, 0.0018 MKH2PO4; pH 7.4); group II (control), in which unchallenged birds were treated with 0.2 mL of bacteriophage EC1 (1011 pfu/ mL); group III, in which birds were challenged with 0.2 mL of a 5-h-old E. coli O78:K80 culture (grown in Luria-Bertani broth at 37°C and shaken at 180 rpm) containing 109cfu of bacterial cells/mL, followed by 0.2 mL of bacteriophage EC1 (1011 pfu/mL) at 2 h postchallenge; and group IV, in which birds were challenged with 0.2 mL of a 5-h-old E. coli O78:K80 culture containing 109 cfu of bacteria cells/mL only. The time point at which to inoculate the bacteriophage (2 h postchallenge) was selected based on the results of a preliminary trial showing that E. coli O78:K80 had colonized the lungs and that the bacteria had spread to other organs, such as the liver and heart, 2 h after the birds were challenged with the pathogen (data not shown). All the materials were inoculated directly intothe trachea of the 1-d-old chicks by using a feeding needle in a farm settingThe BW of live birds were taken weekly. Sampling was carried out on d 0 (before inoculation of E. coli or bacteriophage EC1), 1, 2, 3, 7, 14, and 21 from 3 of the pens of each treatment group. The last pen was used for the observation of mortality rate. On each sampling day, 6 birds from each group (2 randomly selected from each of the 3 sampling pens) were weighed and killed by CO2 inhalation for laboratory examination. Birds that died on the sampling day were also dissected and subjected to the same laboratory examinations. All animal management and sampling procedures complied with the guidelines of the Guide for the Care and Use of Agricultural Animals in Agricultural Research and Teaching (Federation of Animal Science Societies, 1999).Animals and Housing ConditionsA total of 144 specific pathogen-free (SPF) chickens (Valo; Lohmann-Tierzucht, Cuxhaven, Germany) hatched at the Clinic for Avian, Reptile and Fish Medicine, University of Veterinary Medicine, Vienna, Austria, were used in the study. The chickens were distributed randomly and kept under controlled conditions in sterilized isolation units (Montair Andersen B.V. HM 1500, Sevenum, the Netherlands; size: 1.2 m2) with the airflow of 30 to 32 m3/h. The temperature was adjusted at 33°C during the first week of life and later on reduced gradually (2°C per week) to 20°C by the age of 6 wk. Light period was kept at 12 h throughout the trial. Feedand water were provided ad libitumIn experiments, birds were kept under incandescent lighting on a light schedule consisting of 23 h light and 1 h dark. They were provided ad libitum access to water and an unmedicated standard corn and soybean broiler starter diet that met or exceeded the NRC recommended allowances (National Research Council, 1994), and which contained 3,000 kcal of ME/kg and 21.0% CP. Birds were fed an unsupplemented diet or the same diet supplemented with a low level (LL) of 500g/tonne (1lb/ton) or a high level (HL) of 1,000 g/tonne (2 lb/ton) of a standardized yeast extract feed supplement (Alphamune). Individual bird weights and feed consumption by pen were determined weekly.The temperature of the control room was maintained according to established standard operating procedures. Brooders were set at 32.3C for the first week, after which roomtemperature was maintained at 24.8Cstudy using an automated air handling system.At 7 d of age, during the cold-stress treatment, birds were challenged by coarse spray inoculation of eyes and nares with approximately 3 to 4×108 cfu of a nonmotile serotype O2 strain of E. coli that had originally been isolated from chickens with colisepticemia and has been used to reproduce turkey osteomyelitis complex (Huff et al., 1998, 2000). The inoculum was prepared by adding 2 loops of a fresh 18-h culture that was grown on Columbia sheep blood agar at 37 C to 100 mL of tryptose phosphate broth and incubating for 2.5 h in a 37 C shaking waterbath. The culture was serially diluted and held overnight for 18 to 20 h at 4 C while a standard plate count was made and counted.Mortality data were collected twice each day after challenge and birds were weighed and examined for lesions of airsacculitis. The following key, modified from that described by Piercy and West (1976), was used to score lesions of airsacculitis and pericarditis observed in both mortalities and at necropsy: 0 = no inflammation; 1 =opacity and thickening of the inoculated air sac; 2 = mild airsacculitis and mild pericarditis; 3 = moderate airsacculitis or pericarditis with spread to liver or abdominal cavity(perihepatitis or peritonitis); 4 = severe fibrinous airsacculitis and severe pericarditis; and 5 = severe airsacculitis or pericarditis with spread to liver or abdominal cavity.E. coli Challenge CultureThe E. coli used in these studies were initially isolated from the blood of chickens with colisepticemia (Bayyari et al., 1997; Huff et al., 1998). This E. coli strain is serotype 02, nonmotile, and lactose negative. The E. coli culture was prepared by inoculation of tryptose phosphate broth (Sigma Chemical Co., St. Louis, MO) that was incubated in a shaking water bath for 2.5 h. The culture was removed from the water bath and held at 4°C. The culture was enumerated by making duplicate 10-fold serial dilutions of the culture and by spread-plating the appropriate dilutions in duplicate on tryptose phosphate agar plates, which were enumerated after overnight incubation at 37°C. The challenge cultures were made by diluting this E. coli stock culture, and verified with serial dilutions of the challenge culture and enumeration by spread plating.Preparation of Pathogenic EC. Pathogenic EC serotype O2:K1 was cultured overnight in nutrient broth at 37 C. The culture was centrifuged for 15 min at 3400 × g, washed, and resuspended in PBS (pH 7.4). Bacterial concentration was measured by a spectrophotometer (570nm). Each chick received 0.1 mL of bacterial suspension (1 × 1010 cfu/mL in PBS).Laboratory Examinations Gross Lesion Examinations.Macroscopic examinations of the air sac, liver, and heart of slaughtered birds were carried out. Opacity or thickening of the air sac and the presence of tissue lesions or fibrinous exudates on the liver and heart were considered indicative of airsacculitis,perihepatitis, andpericarditis, respectively.Organ Weight.At necropsy, the lung, liver, heart, and spleen were excised aseptically and weighed. The weights of the organs were reported as the percentage relative to BW (organ weight/BW × 100%; Huff et al., 2006a).Isolation of E. coli from Lungs (Quantitative Analysis).The lungs of birds were removed aseptically,weighed, diluted 10× in Maximum Recovery Diluent(Merck KGaA, Darmstadt, Germany), and homogenized.The homogenates were then serially diluted before plating on eosin methylene blue (EMB) agar(Merck KGaA). The EMB agar plates were incubated overnight at 37°C, after which the metallic green sheen colonies of E. coli (designated EMB + E. coli) were counted to determine the number of E. coli (cfu/g) colonizing the lungs. The populations of EMB + E. coli in lung samples from birds in the different treatment groups were then compared to determine the severity of infection.Isolation of E. coli from Organs and Blood.Blood samples of birds were collected by cardiac puncture and cultured on EMB agar. The liver, heart, and spleen of each bird were cut open, and the inner parts of these organs were swabbed 3 to 4 times with sterile cottonbuds and plated directly on EMB agar. The plates were then incubated at 37°C for 16 to 18 h, and the presenceof E. coli colonies (designated EMB + E. coli) was determined.Scoring Scheme and Laboratory ProceduresClinical Scores.The health status of the birds was scored from 0 to 4 on the basis of following criteria: 0 = animal active with no clinical symptoms; 1 = slightly weak, dropping wings, diarrhea; 2 = depressed with swollen crop; 3 = weak with ruffled feathers, reluctant to walk, and apathy; and 4 = animal unable to move or stand, eyes closed, and intense breathing. The health status was scored daily from day of inoculation to the day of termination of experiment.Gross Pathological Lesion Score.Tissue lesions from liver and heart were scored according to Mellata et al. (2003). The scoring scale for different organs was as follows: (i) Liver: 0 = normal; 1 = slight amounts of fibrinous exudate; 2 = marked perihepatitis. (ii) Heart and pericardium: 0 = normal; 1 = vascularization, opacity, cloudy fluid in the pericardial cavity; 2 = acute pericarditis. (iii) Lung: 0 = normal; 1 = edema; 2 = edema and hyperaemia; 3 = edema, hyperemia and fibrin in air sacs. (iv) Spleen: 0 = normal; 1 = swollen 2 = fibrinated bedding.Bacteriological Examinations of Tissues (Qualitative Examination).The presence of the bacterial strain used for infection was determined qualitatively by streaking the samples from liver, lung, heart, and spleen directly on McConkey agar plates. The plates were incubated overnight at 37°C for 24 h and observed for the presence of E. coli.Bacterial Recovery (Quantitative Examination).Liver, heart, lung, and spleen (100 to 200 mg) were homogenized in 1 to 2 mL of PBS and 100 μL of serial dilutions of the homogenate were spread on McConkey agar plates for bacterial quantification. Moreover, 1 mL of the homogenate was incubated overnight in LB brothto investigate the presence of E. coli in the tissue samples given above.Hematology and Clinical Biochemistry. Hematological investigations were performed on heparinized blood samples taken from birds during euthanization. Erythrocyte counts and PCV were measured following Swarup et al. (1986), whereas granulocytes were counted using eosinophil unopette method (Campbell, 1995). For erythrocyte counts the blood was diluted (1:200) in Natt and Herrick (1952) solution, and for granulocyte count it was diluted (1:20) in unopette solution, which stains only heterophils and eosinophils, the number of cells were counted in 9-mm area in a Neubauer chamber.For clinical biochemistry, plasma was separated by centrifuging blood at 3,380 × g for 15 min, and GOT, LDH, ALP, total protein, and albumin were measured on automated clinical chemistry analyzer Hitachi 911 (Roche Diagnostics, Mannheim, Germany) with reagent test kits supplied by Roche. Globulin was determined as a difference between total protein and albumin (Varley, 1975).Humoral Immune Response.Antibodies against SRBC were measured by quantifying total antibody titer in addition to mercaptoethanol sensitive IgM and mercaptoethanol resistant IgG using microagglutination assay (Delhanty and Solomon, 1966). Briefly, 2-fold serial dilutions of serum were prepared in PBS in microtiter plates; later, an equal volume of 1% SRBC in PBS was placed in all wells. Plates were shaken for 1 min and incubated for 1 h at 37°C for total antibody titer. The agglutination titer was expressed as log2 of the highest dilution of sera giving visible agglutination. For IgG the test was performed exactly in the same manner except that the plasma was incubated with equal volume of 0.2 M of 2-mercaptoethanol for 1 h at room temperature before making 2-fold dilutions. The IgM was calculated as a difference of total immunogloubin and IgG titer. Primary antibody titer against SRBC was estimated from the serum samples collected after 10 d of first exposure to SRBC, whereas the secondary antibody titer was estimated from the sera taken at the day of termination of the experiment.Cell-Mediated Immune Response. The PHA skin test for T-cell-mediated immunity was conducted in 41-d-old chickens following the procedures of Grasman and Scanlon (1995) using a 0.1 mL dose of 1 mg/mL of PHAP (Sigma, St. Louis, MO) in PBS. Feathers were plucked from both wing webs. One wing was injected with PHA, whereas the other received a placebo injection of PBS alone. The thickness of each wing web was measured to the nearest 0.05 mm immediately before and 24 ± 3 h after the injections, using vernier caliper with the precision of 0.01 mm.A stimulation index was calculated as the change in the thickness of the PHA-injected wing web minus the change in thickness of the PBS-injected wing web.Microbial Populations EnumerationFresh ileac and cecal samples (0.5 g) were diluted with 9.5 mL of sterilized distilled water and vortexed until a pH of 6.0 was obtained. One gram of wet sample was diluted with 10 mL of distilled water, of which 1 mL was transferred into 9 mL of sterilized distilled water. Samples were serially diluted from 10−1 to 10−7. One-tenth milliliter of each diluted sample was coated on the appropriate medium for enumeration of microbial populations. Bacterial counts were performed using the appropriate dilution and plate culture techniques under aerobic or anaerobic conditions according to Barnes and Impey (1970), and the results were expressed as colony-forming units log10 per gram of fresh sample. The bacterial groups and species determined included lactobacilli (LBS agar), Escherichia coli (Mac- Conkey agar), and bifidobacteria (bifidobacterium agar composed of tomato juice, 400 mL; dissoluble amylum, 0.5 g; peptone, 15 g; yeast extract, 2 g; glucose, 20 g; sodium chloride, 5 g; Tween-80, 1 mL; 5% cysteine, 0.5 mL; liver extract, 80 mL; agar powder, 20 g; and distilled water, 520 mL; pH = 7.0) incubated at 37°C for 72 h.Statistical AnalysisThe data were analyzed using 1-way ANOVA, followed by Duncan’s multiple range test. Fisher’s exact tests were performed to determine significant differences between the untreated and treated E. coli-challenged groups for isolation of EMB + E. coli from different organs and the presence of gross lesions. A chi-squared test was used to analyze the effect of bacteriophage EC1 on the mortality of birds. All analyses were performed using SPSS software for Windows version 13 (SPSS Inc., Chicago, IL). A P-value of <0.05 was considered statistically significant.Statistical AnalysisAll results were presented as means. Experimental data were analyzed using the SPSS for Windows statistical package program, version 8.0.0 (SPSS Inc., Chicago, IL). Comparisons of the means were performed using Duncan’s multip le range test. Significance was defined as a P-value of ≤0.05%.DiscussionYeast extract supplementation significantly improved both the BW and the feed:gain ratio of the poults challenged with E. coli.Immunostimulation using yeast extract supplements may protect poults from young breeder flocks from some of the production loss due to cold stress and E. coli infection but may sometimes be detrimental to birds not needing immunostimulation.An immune-mediated pathology due to inflammation may also have led to the reported increase in mortality in MOS-supplemented poults that were orally challenged with E. coli (Fairchild et al., 2001).Fairchild, A. S., J. L. Grimes, F. T. Jones, M. J. Wineland, F. W. Edens, and A. E. Sefton. 2001. Effects of hen age, Bio-Mos, and Flavomycin on poult susceptibility to oral Escherichia coli challenge. Poult. Sci. 80:562–571.Escalating consumer concerns regarding pathogen resistance have placed the poultry industry under mounting pressure to eliminate the use of chemotherapeutic agents as feed additives. One possible alternative receiving increased attention is the use of immunomodulators such as β-glucan. A study was conducted to investigate the effects of a yeast-derived β-glucan (Auxoferm YGT)on broiler chick performance, lesion scores, and immune-related gene expression during a mixed Eimeria infection. Day-old chicks were fed diets containing 0, 0.02, or 0.1% YGT. On d 8 posthatch,one-half of the replicate pens were challenged with a mixed inoculum of Eimeria acervulina, Eimeria maxima, and Eimeria tenella. Measurements were taken and samples collected on d4, 10, 14, and 21 posthatch. Dietary supplementation had no effect on performance or mortality. On d 14, 3 birds per pen(n = 24/treatment) were scored for intestinal coccidia lesions. Gross lesion severity was significantly reduced in birds supplemented with 0.1% YGT. On d 10, inducible nitric oxide synthase (iNOS)expression was downregulated in the jejunum of challenged birds fed 0.1% YGT. Expression of iNOS in the ileum was downregulated in the nonchallenged birds, but upregulated in the challenged birds fed 0.1% YGT on d 14. Interleukin (IL)-18 was upregulated in the jejunum of 0.1% YGT-treated birds. Interferon (IFN)-expression was decreased in challenged and nonchallenged birds fed 0.1% YGT. The IL-4 expression was downregulated in the nonchallenged birds with 0.1% YGT diet supplementation. The IL-13 and mucin-1levels were also reduced due to β-glucan supplementation.Mucin-2 expression was increased in the nonchallenged birds,but decreased in the infected birds fed 0.1% YGT. These results suggest that although Auxoferm YGT at doses of 0.02 and 0.1%does not influence performance, it significantly reduces lesion severity and is capable of altering immune-related gene expression profiles, favoring an enhanced T helper type-1 cell response during coccidiosis.Immune responses to dietary β-glucan in broiler chicks during an Eimeria challengeC. M. Cox*, L. H. Sumners*, S. Kim*, A. P. McElroy*, M. R. Bedford and R. A. Dalloul Poult Sci 2010. 89:2597-2607. doi:10.3382/ps.2010-00987Performance and immune responses to dietary β-glucan in broiler chicksC. M. Cox*, L. H. Stuard*, S. Kim*, A. P. McElroy*, M. R. Bedford and R. A. Dalloul*,1* Avian Immunobiology Laboratory, Department of Animal and Poultry Sciences, Virginia Tech, Blacksburg 24061; and AB Vista Feed Ingredients, Marlborough, Wiltshire, SN8 4AN, United Kingdom1 Corresponding author: RDalloul@During the first week posthatch, the avian immune system is immature and inefficient at protecting chicks from invading pathogens. Among immunomodulators, β-glucan s are known as biological response modifiers due to their ability to activate the immune system. Current research suggests that β-glucan s may enhance avian immunity; however, very little is known about their influence on regulation of immune function. A study was performed to evaluate the effects of dietaryβ-glucan on growth performance, immune organ weights, peripheral blood cell profiles, and immune-related gene expression in the intestine.One-day-old chicks were fed a diet containing 0, 0.02, or 0.1%yeast β-glucan (n = 30/treatment). On d 7 and 14 posthatch,body and relative immune organ weights were measured and small intestinal sections were collected to evaluate gene expression by quantitative real-time PCR. Peripheral blood samples were also collected to determine heterophil:lymphocyte ratios. Supplementation of β-glucan did not significantly affect BW gains, and no significant differences were observed among groups for relative immune organ weights or heterophil:lymphocyte ratios. Compared with controls, expression of interleukin (IL)-8 was downregulated in the β-glucan-treated groups on d 7 and 14. On d 14,β-glucan inclusion resulted in increased inducible nitric oxide synthase expression. Expression of IL-18 was upregulated on d 7 but reduced on d 14 due to β-glucan supplementation.On d 7, interferon-and IL-4 expression decreased in the β-glucan-treated groups. However, on d 14, IL-4 expression was upregulated in the supplemented groups. Intestinal expression of IL-13 was also downregulated in the β-glucan-treated birds on d 7.These results suggest that dietary inclusion of β-glucan s altered the cytokine-chemokine balance; however, it did not elicit a robust immune response in the absence of a challenge,resulting in no deleterious effects on performance.Key Words:β-glucan• broiler • cytokine • immunityPoult Sci 2010. 89:1924-1933.Efficacy of a bacteriophage isolated from chickens as a therapeutic agent for coli bacillosis in broiler chickensG. L. Lau*, C. C. Sieo*,,1, W. S. Tan*,, M. Hair-Bejo, A. Jalila and Y. W. Ho* Department of Microbiology, Faculty of Biotechnology and Biomolecular Sciences, Institute of Bioscience, Department of Veterinary Pathology and Microbiology, Faculty of Veterinary Medicine, and Department of Veterinary Clinical Studies, Faculty of Veterinary Medicine, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor, Malaysia1 Corresponding author: ccsieo@.myThe efficacy of bacteriophage EC1, a lytic bacteriophage, against Escherichia coli O78:K80, which causes coli bacillosis in poultry,was determined in the present study. A total of 480one-day-old birds were randomly assigned to 4 treatments groups, each with4 pens of 30 birds. Birds from the control groups (groups I and II) received PBS (pH 7.4) or 1010 pfu of bacteriophage EC1,respectively. Group III consisted of birds challenged with 108 cfu of E. coli O78:K80 and treated with 1010 pfu of bacteriophage EC1 at 2 h post infection, whereas birds from group IV were challenged with 108 cfu of E. coli O78:K80 only. All the materials were introduced into the birds by intratracheal inoculation. Based on the results of the present study, the infection was found to be less severe in the treated E. coli-challenged group. Mean total viable cell counts of E. coli identified on eosin methylene blue agar (designated EMB + E. coli) in the lungs were significantly lower in treated, E. coli-challenged birds than in untreated,E. coli-challenged birds on d 1 and 2 post infection. The EMB+ E. coli isolation frequency was also lower in treated birds;no E. coli was detectable in blood samples on any sampling day,and E. coli were isolated only in the liver, heart, and spleen of treated chickens at a ratio of 2/6, 1/6, and 3/6, respectively,at d 1post infection. The BW of birds from the E. coli-challenged group treated with bacteriophage EC1 were not significantly different from those of birds from both control groups but were15.4% higher than those of the untreated, E. coli-challenged group on d 21 post infection. The total mortality rate of birds during the 3-wk experimental period decreased from 83.3% in the untreated, E. coli-challenged birds (group IV) to 13.3%in birds treated with bacteriophage EC1 (group III). These results suggest that bacteriophage EC1 is effective in vivo and could be used to treatcoli bacillosis in chickens.Key Words:bacteriophage • Escherichia coli• coli bacillosis • broilerPoult Sci 2010. 89:2589-2596Bacterial clearance, heterophil function, and hematological parameters of transport-stressed turkey poults supplemented with dietary yeast extract1G. R. Huff*,2, W. E. Huff*, M. B. Farnell, N. C. Rath*, F. Solis de los Santos and A. M. Donoghue** USDA, Agricultural Research Service, Poultry Production and Product Safety Research Unit, Fayetteville, AR 72701; Poultry Science Department, Texas A&M University, College Station。
加巴喷丁在临床疼痛治疗中的应用
Motor Phenomena ,PMP and NMP）。
感觉异常：痛、触、温度 痛觉异常（allodynia ） 痛觉过敏（hyperalgesia ） 触物痛感（dysesthesia ） 感觉异常 (paresthesia ) 感觉减退（hypoesthesia ） 感觉缺失（anesthesia） 感觉迟钝(dysesthisias)
常见的神经痛
➢ 神经病理性疼痛(Neuropathic Pain,NP) ➢ 带状疱疹后遗神经痛(Postherpetic Neuralgia,PHN) ➢ 糖尿病性周围神经病 (Diabetic Peripheral Neuropathy,DPN) ➢ 痛性糖尿病神经病(Painful Diabetic Neuropathy,PDN) ➢ 复杂性区域疼痛综合征(Complex Regional Pain Syndrome,CRPS) ➢ 三叉神经痛(Trigeminal Neuralgia,TN ) ➢ 舌咽神经痛(Glossopharyngeal Neuralgia,GPN ) ➢ 残肢痛(Stump Pain,SP) ➢ 幻肢痛(Phantom Limb Pain,PLP)
神经病理性疼痛的机制
目前认为，疼痛 产生于损伤的神经轴 突和邻近的背根神经 节传来的异位冲动。
神经损伤部位及其相邻的背跟神经节 的神经元发生病理改变----神经元细胞
膜钠通道密度增加和重分布
轴突电生理特性重塑 导致外周敏化
自主和异位放电增加
异常传入冲动影响中枢 导致中枢敏化
导致感觉异常、感觉迟钝和疼痛。
加巴喷丁 在疼痛治疗中的临床应用
三种布鲁氏菌病疫苗株的毒力比较
三种布鲁氏菌病疫苗株的毒力比较程君生;吴梅花;赵丽霞;彭小兵;丁家波;王楠;夏业才;毛开荣【摘要】为系统比较我国现有布鲁氏菌病疫苗株A19、M5和S2的毒力,分别用上述3种疫苗株以1×105CFU/只免疫Balb/c小鼠,免疫后每隔2周采集小鼠脾脏,分离细菌,测定各疫苗株在小鼠脾脏中的存留时间。
结果 A19、M5、S2在小鼠体内存活时间依次为14周、大于16周、6周。
将以上3种疫苗株分别以1×109CFU/只免疫Hartley豚鼠,15日后测定豚鼠脾脏含菌量,结果 A19、M5、S2免疫后每克脾脏含菌量分别为2.8×104CFU、大于6.7×105CFU、3.8×103CFU。
研究结果表明,我国目前使用的布鲁氏菌疫苗中,S2毒力最弱,A19其次,M5最强。
%In order to compare the virulence of the applied vaccine strains of brucellosis,which are B.abortus A19,B.melitensis M5 and B.suisS2,three groups of above va ccines with the dose of 1×105 CFU each were inoculated to female Balb/c mice,respectively.The specific bacterica were isolated and identified by PCR from the spleens of each group every 2 weeks post inoculation.The suvival tests shows that A19,M5 and S2 strains could stay in spleen for 14 weeks,more than 16 weeks and 6 weeks post inoculation,respectively.The same dose of bacterias were injected to adult female guinea pigs in groups,respectively,and the amount of ioslated bacteria were calculated for each group of spleens per grame.The amount of containing bacteria for group A19,M5 and S2 were 2.8×104CFU,more than 6.7×105 CFU and 3.8×103CFU.This study shows that in all the three kinds of brucella vaccines,S2 is the weakest strain,while M5 is the strongest one.【期刊名称】《中国兽药杂志》【年(卷),期】2012(046)009【总页数】3页(P1-3)【关键词】布鲁氏菌;疫苗;毒力【作者】程君生;吴梅花;赵丽霞;彭小兵;丁家波;王楠;夏业才;毛开荣【作者单位】中国兽医药品监察所,北京100081;金宇保灵生物药品有限公司,呼和浩特010030;金宇保灵生物药品有限公司,呼和浩特010030;中国兽医药品监察所,北京100081;中国兽医药品监察所,北京100081;中国兽医药品监察所,北京100081;中国兽医药品监察所,北京100081;中国兽医药品监察所,北京100081【正文语种】中文【中图分类】S859.797布鲁氏菌病(简称布病)是一种世界范围流行的人畜共患病，严重威胁人类和多种动物的生命健康，造成巨大的经济损失。
FM 对自动喷淋系统要求
Байду номын сангаасClass Number 1630
November 2013
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