Calcium mediates root K +/Na +homeostasis in poplar species di?ering in salt tolerance
JIAN SUN,1,*SONGXIANG DAI,1,*RUIGANG WANG,1,*SHAOLIANG CHEN,1,2,3,**NIYA LI,1XIAOYANG ZHOU,1CUNFU LU,1XIN SHEN,1XIAOJIANG ZHENG,2ZANMIN HU,4ZENGKAI ZHANG,5JIN SONG 5and YUE XU 5
1College of Biological Sciences and Technology,Beijing Forestry University,P.O.Box 162,Beijing 100083,P.R.China
2
Key Laboratory of Biological Resources Protection and Utilization in Hubei Province,Hubei University for Nationalities,Enshi 445000,P.R.China
3Corresponding author (lschen@https://www.doczj.com/doc/4115408526.html,)
4Institute of Genetics and Developmental Biology,Chinese Academy of Sciences,Beijing 100101,P.R.China
5
Xuyue (Beijing)Science and Technology Co.,Ltd.,Yingzhi Dasha 601,Suzhoujie Street 49-3,Haidian District,Beijing 100080,P.R.China
Received February 20,2009;accepted June 11,2009
Summary Using the non-invasively ion-selective micro-electrode technique,?ux pro?les of K +,Na +and H +in mature roots and apical regions,and the e?ects of Ca 2+on ion ?uxes were investigated in salt-tolerant poplar species,Populus euphratica Oliver and salt-sensitive Populus simonii ·(P.pyramidalis +Salix matsudana )(Populus popularis 35-44,P.popularis ).Compared to P.popularis ,P.euphratica roots exhibited a greater capacity to retain K +after exposure to a salt shock (SS,100mM NaCl)and a long-term (LT)salinity (50mM NaCl,3weeks).Salt shock-induced K +e?ux in the two species was markedly restricted by K +channel blocker,tetraethylammonium chloride,but enhanced by sodium orthovanadate,the inhibitor of plasma membrane (PM)H +-ATPase,suggesting that the K +e?ux is mediated by depolarization-activated (DA)channels, e.g.,KORCs (outward rectifying K +channels)and NSCCs (non-selective cation channels).Populus euphratica roots were more e?ective to exclude Na +than P.popularis in an LT experiment,resulting from the Na +/H +antiport across the PM.Moreover,pharmacological evidence implies that the greater ability to control K +/Na +homeostasis in salinized P.euphratica roots is associated with the higher H +-pumping activity,which provides an electrochemical H +gradient for Na +/H +exchange and simultaneously decreases the NaCl-induced depolarization of PM,thus reducing Na +in?ux via NSCCs and K +e?ux through DA-KORCs and DA-NSCCs.Ca 2+application markedly
limited salt-induced K +e?ux but enhanced the apparent Na +e?ux,thus enabling the two species,especially the salt-sensitive poplar,to retain K +/Na +homeostasis in roots exposed to prolonged NaCl treatment.
Keywords:K +?ux,NaCl,Na +/H +antiport,Populus euphratica,Populus popularis,the scanning ion-selective electrode technique,X-ray microanalysis.
Introduction
Physiological mechanisms underlying the salt tolerance of Populus euphratica Oliver,a valuable tree species used for a?orestation on saline and alkaline desert sites,have received much attention in recent years.Populus euphratica plants are able to maintain ionic homeostasis after a pro-longed salt exposure (Chen et al.2001,2002a ,2003,Ottow et al.2005a ,Sun et al.2009).However,NaCl stress usually perturbs ion homeostasis in salt-sensitive poplar species,leading to oxidative bursts and salt damage (Wang et al.2006,2007,2008).It is suggested that the capacity to retain lower cytosol Na +is critical for plant salt adaptation (Maathuis and Amtmann 1999,Blumwald et al.2000,Hasegawa et al.2000,Zhu 2001,2003,Apse and Blumwald 2007,Munns and Tester 2008,Shabala and Cuin 2008).In addition to reducing Na +in?ux,compartmentalizing Na +into the vacuole and extruding Na +to the apoplast are the two important strategies of plant cells to avoid excessive accumulation of Na +in the cytosol.
The signi?cance of vacuolar sequestration by tonoplast Na +/H +antiporters has been con?rmed by transgenic plants (Apse et al.1999,Ohta et al.2002,Parks et al.2002,Fukuda et al.2004).An evident vacuolar Na +
*
These authors contributed equally to this work as ?rst authors.**
Present address:College of Biological Sciences and Technol-ogy,Beijing Forestry University,P.O.Box 162,Beijing 100083,P.R.China.
Tree Physiology Page 1of 12doi:10.1093/treephys/tpp048
óThe Author 2009.Published by Oxford University Press.All rights reserved.For Permissions,please email:journals.permissions@https://www.doczj.com/doc/4115408526.html,
Tree Physiology Advance Access published July 28, 2009
compartmentation was shown in salinized P.euphratica cells in our previous reports(Chen et al.2000,2002a, 2003).At the plasma membrane(PM),SOS1functions as a Na+/H+antiporter in Arabidopsis to extrude excess Na+from the cytosol(Shi et al.2000,2003).The gene encoding PeSOS1,a putative PM Na+/H+antiporter in P.euphratica,has been recently characterized by Wu et al.(2007).They found that the level of expressed PeSOS1 protein in P.euphratica leaves was signi?cantly up-regulated in the presence of200mM NaCl(Wu et al. 2007).Our results suggest that the Na+extrusion in P.euphratica likely results from another type of Na+/H+ antiporter,PeNhaD1.Yeast complementary experiments showed that the introduction of PeNhaD1rescued the nor-mal growth of ANT3(Saccharomyces cerevisiae mutant strain ANT3,D ena1-4::HIS3D nha1::LEU2),which lacks the PM Na+/H+antiporter gene ScNHA1,in the presence of80mM NaCl on a solid medium or in a liquid medium of400mM NaCl(Lu et al.2007).Transcript level of PeNhaD1remained constant in P.euphratica under salt stress but declined in the salt-sensitive poplar(Ottow et al.2005b).Moreover,overexpression of PeNhaD1in a salt-sensitive poplar species was found to increase the Na+exclusion in transgenic plants(Chen2007).
H+-ATPase provides a driving force for Na+/H+ exchange and its activity in the vesicles of tonoplast and PM was up-regulated when P.euphratica calluses were exposed to NaCl stress(Ma et al.2002,Zhang et al. 2007,Yang et al.2007a).Yang et al.(2007b)suggest that Na+movement across vesicle membranes is highly depen-dent on H+-ATPase.In addition to providing a driving force for Na+extrusion,H+-ATPase may inhibit the entry of Na+by repolarizing the PM,as external NaCl usually depolarizes the PM and causes a massive Na+in?ux via VI-NSCCs(voltage-independent non-selective cation chan-nels)(Maathuis and Sanders2001,Demidchik and Tester 2002,Demidchik et al.2002,Tester and Davenport2003, Maathuis2006).Little is known about the correlation between H+pumping and Na+extrusion in long-term (LT)-stressed woody plants.
NaCl-induced K+de?ciency in plants is suggested to result from(1)uptake reduction–Na+competes with K+for uptake sites at the PM,including both low-a?nity (e.g.,NSCCs)and high-a?nity transporters(e.g.,HKTs) and(2)K+leakage through depolarization-activated out-ward rectifying K+channels(DA-KORCs),or both(1) and(2)(Demidchik and Maathuis2007,Shabala and Cuin 2008).The correlation between K+e?ux and the capacity for salinity resistance has been established in crop species. Electrophysiological evidence indicates that NaCl-induced K+loss in the roots of barley and wheat is signi?cantly lar-ger in salt-sensitive cultivars than in salt-tolerant cultivars (Chen et al.2005,2007,Cuin et al.2008).Comparative studies have shown that salinized P.euphratica exhibits a higher capacity in nutrient uptake and transport at both the tissue and cellular levels(Chen et al.2000,2001,2002b,2003).Expression analyses of a salt-sensitive poplar, Populus·canescens,revealed that ion channels able to release K+,PTORK(KORC),PTORK2(KORC2)and PTK2(K+channel2),showed remarkable up-regulation during salt stress in roots(Escalante-Pe rez et al.2009). The immediate response of K+to NaCl addition was repeatedly reported;however,salt-induced alternations of root K+?ux have not been investigated after exposure to a prolonged salinity.
It is widely established that Ca2+ameliorates Na+toxic-ity in a variety of plant species(Caines and Shennan1999, Hasegawa et al.2000,Shabala et al.2003,Arshi et al.2005, Renault2005).Ca2+is essential for ionic homeostasis and K+/Na+ratio was increased by Ca2+supplement in sos3 mutant and wild-type Arabidopsis(Liu and Zhu1997).It is suggested that Ca2+restricts the entry of Na+through permeable NSCCs(Demidchik et al.2002,Tester and Davenport2003,Demidchik and Maathuis2007)and inhibits K+loss via both the DA-KORCs and NSCCs (Shabala et al.2006).However,how Ca2+a?ects?ux pro-?les of K+and Na+in LT-stressed poplars needs to be elucidated.
In this study,we applied the scanning ion-elective elec-trode technique(SIET)to clarify species-speci?c di?erences in ionic homeostasis control by mapping K+,Na+and H+?ux pro?les from roots of two contrasting poplar species, the salt-tolerant P.euphratica and salt-sensitive Populus popularis35-44.Moreover,the contribution of Ca2+to K+/Na+homeostasis was examined in the two tested pop-lars.We compared the ion?ux pro?les from poplar roots after a prolonged exposure to salinity.This is necessary to clarify plant adaptations to long durations of salinity; so far,most of the reports on salinity e?ects on root ion ?uxes were obtained for acute stress conditions. Materials and methods
Plant materials
Plants of the two poplar species were prepared as described previously(Sun et al.2009).Brie?y,in April2008,seedlings of P.euphratica,obtained from the XinJiang Uygur Auton-omous Region of China and hardwood cuttings of P.pop-ularis35-44(P.popularis),from the nursery of Beijing Forestry University(BFU),were planted in individual pots (10l)containing loamy soil and placed in a greenhouse at BFU.Plants were well irrigated and fertilized with 1000ml full-strength Hoagland’s nutrient solution every 2weeks.Potted plants were raised for1month before the beginning of hydroponic culture.In mid-May,uniform plants were washed free of soil and transferred to individual porcelain pots containing2000ml quarter strength Hoagland’s nutrient solution.Hydroponic cultures,aerated by air pumps,were renewed every2days.The temperature in the greenhouse was20–25°C with a16-h photoperiod (7:00–23:00),150l mol mà2sà1of photosynthetically
2SUN ET AL.
TREE PHYSIOLOGY
active radiation.Plants were cultured for20days in hydro-ponics before experiments.
A LT NaCl treatment
The same three treatments were applied to the two species: control,NaCl(50mM)and NaCl(50mM)plus Ca2+ (10mM).The required amount of NaCl and CaCl2was added to the nutrient solution.Control plants were well fer-tilized but treated without the addition of NaCl or CaCl2. Plants were continuously aerated by passing air to hydro-ponics,which was regularly renewed.Steady?uxes of K+,H+and Na+in apical and mature roots were mea-sured after7,14and21days of treatment,respectively. At the?nal harvest,root segments with1.0cm apices were sampled,freeze-dried and used for X-ray microanalysis by means of scanning electron microscope equipped with an energy dispersive X-ray spectrometer(SEM-EDAX).
X-ray microanalysis
Roots,sampled from control and stressed plants,were imme-diately cut with a razor blade,rapidly frozen in liquid nitro-gen,vacuum freeze-dried atà100°C for100h and then slowly allowed to equilibrate to room temperature(ca. 22°C)over a period of24h.Freeze-dried samples were gold-coated in a high vacuum sputter coater and analysed with a Hitachi S-3400N SEM-EDAX(EX-250;Horiba Ltd.,Kyoto,Japan).Probe measurements of roots were taken with a broad electron beam covering the whole cross section.Relative amount of K+or Na+was expressed as a percentage of the total atomic number for all the major elements(K+,Na+,Ca2+,Mg2+and Clà)that were detected from the root sections.
Flux measurements with SIET
Net K+,H+and Na+?uxes were measured non-invasively using the SIET(the SIET System,BIO-001A,Younger USA Sci.&Tech.Corp.,Amherst,MA)(Ku htreiber and Ja?e1990,Kochian et al.1992,Zonia et al.2002,Vincent et al.2005,Xu et al.2006,Sun et al.2009).The concentra-tion of target ions and concentration gradients were mea-sured by moving the electrode repeatedly between two positions adjacent to plant materials in a pre-established excursion(30l m)at a programmable frequency in the range of0.3–0.5Hz.The SIET can measure ion concentra-tions down to picomolar levels but must be measured slowly at about1–2s per point.This is mainly due to the mechanical disturbance of the gradient by the electrode movement(it usually takes a fraction of a second to reestablish the gradient)(Kunkel et al.2006). Preparations of ion-selective electrodes were performed as follows:glass micropipettes(2–4l m aperture)were pulled from1.5mm diameter glass capillaries(TW150-4;World Pre-cision Instruments,Inc.,Sarasota,FL)with an electrode puller(P-97;Sutter Instrument Co.,Novato,CA)using a four-step pulling.Pulled micropipettes were silanized with dimethyldichlorosilane(D3879;Sigma,St.Louis,MO)at 250°C for50min and back-?lled with back?lling solution (H+:40mM KH2PO4and15mM NaCl,pH7.0;K+: 100mM KCl;Na+:100mM NaCl)to a length of10l m from the tip.Then,the electrodes were front-?lled with a 15-l m column of selective liquid ion-exchange(LIX)cocktail (H:Fluka95293;K:Fluka60398;and Na:Fluka71178).An Ag/AgCl wire electrode holder(EHB-1;World Precision Instruments,Inc.,Sarasota,FL)was inserted in the back of the electrode to make an electrical contact with the electrolyte solution.The reference electrode was an Ag/AgCl half-cell (DRIREF-2;World Precision Instruments,Inc.,Sarasota, FL)connected to the experimental solution by a0.5% agarose bridge containing3M KCl.Ion-selective electrodes were calibrated before and after?ux measurements in the following solutions:
(1)Na+:0.1,0.5and1.0mM(Na+concentration was
0.1mM in the measuring solution because the?uxes of
Na+were only recorded at lower Na+concentrations using the Na LIX,Fluka71178)(Sun et al.2009). (2)H+:pH5.0,6.0and7.0(pH was adjusted to6.0with
NaOH and HCl in the measuring solution).
(3)K+:0.1,0.5and 1.0mM(K+concentration was
0.5mM in the measuring solution).
Only electrodes with Nernstian slopes>50mV/decade were used in our experiments.Flux rate was calculated from Fick’s law of di?usion:
J?àDed c=d xT;
where J represents the ion?ux in the x direction,d c/d x is the ion concentration gradient and D is the ion di?usion constant in a particular medium.Data and image acquisi-tion,preliminary processing,control of the three-dimen-sional electrode positioner and stepper-motor-controlled ?ne focus of the microscope stage were performed with ASET software[Science Wares(East Falmouth,MA) and Applicable Electronics].
Experimental protocols for SIET measurements
Steady-state SIET measurements Root segments with ca.30mm apices were sampled from control and LT-stressed plants at day7,14and21,respectively.To decrease the in?uence of Na+release(especially from the surface of LT-stressed roots)on?ux recording,roots were rinsed with re-distilled water and immediately incubated in the follow-ing solutions to equilibrate for30min(Sun et al.2009): (1)K+and H+measuring solutions:basic solution
(0.1mM NaCl,0.1mM MgCl2,0.1mM CaCl2and
0.5mM KCl)supplemented with50mM NaCl,or
50mM NaCl plus10mM CaCl2,according to corresponding treatments,pH6.0was adjusted with
CALCIUM MEDIATES ROOT K+/Na+HOMEOSTASIS IN POPLAR SPECIES3 TREE PHYSIOLOGY ONLINE at https://www.doczj.com/doc/4115408526.html,
NaOH and HCl.Control roots were equilibrated in the basic solution in the absence of additional NaCl or CaCl2.
(2)Na+measuring solution:basic solution(0.1mM
NaCl,0.1mM MgCl2,0.1mM CaCl2and0.5mM KCl),pH6.0was adjusted with KOH and HCl. After equilibration,roots were transferred to the measuring chamber containing10ml fresh measuring solution and the roots were immobilized on the bottom.Ion?uxes were mea-sured along the root axis at two regions:apex(200–2000l m from the tip with a300-l m measuring interval)and mature zone(10–12mm from the tip with a500-l m measuring inter-val).A2-min continuous recording was performed at each measuring point in both mature and apical regions.
Transient?ux kinetics Control roots of the two species were sampled,rinsed with re-distilled water and immediately equilibrated in basic solution for30min.Thereafter,steady ?uxes of K+and H+were recorded for5–6min before the salt addition.Then,a salt shock(SS,100mM NaCl)was given by adding an acquired amount of NaCl stock(0.2M, pH6.0adjusted with NaOH and HCl)and transient ion ?uxes were monitored for a further35–40min in the apical region(ca.500l m from the root tip)and mature zone(ca. 12mm from the root tip),respectively.The data measured during the?rst2–3min were discarded due to the di?usion e?ects of stock addition(Shabala2000).
E?ects of Ca2+and PM transport inhibitors on transient ?ux kinetics Pharmacological experiments were con-ducted at the apex that had vigorous?ux rates upon NaCl stress.Before the NaCl shock,roots of two species were subjected to one of the three treatments for40min: (1)20mM tetraethylammonium chloride(TEA,K+
channel blocker).
(2)500l M sodium orthovanadate(the speci?c inhibitor
of PM H+-ATPase).
(3)10mM CaCl2.
Transient K+kinetics upon SS(100mM NaCl)were recorded in these roots pretreated with Ca2+or PM trans-port inhibitors.The measuring solution containing sodium orthovanadate was replaced with a fresh solution before the NaCl shock.Measuring solutions with TEA or Ca2+were not renewed because they had no obvious in?uence on the Nernstian slopes of K+electrodes.Na+?ux response to NaCl shock was not attempted due to the lower signal/ noise(S/N)ratio of Na+LIX(Fluka71178)at higher external Na+solution(Sun et al.2009).Transient H+ kinetics upon SS(100mM NaCl)were recorded in vana-
date-pretreated roots of P.euphratica,because this species showed a more pronounced H+?ux under NaCl stress, as compared to P.popularis.Controls were pretreated with-out Ca2+or any inhibitor before NaCl addition.Data analysis Three-dimensional ionic?uxes were calculated using MageFlux developed by Yue Xu, https://www.doczj.com/doc/4115408526.html,/mage?ux,or https://www.doczj.com/doc/4115408526.html,/ mage?ux.
4SUN ET AL.
TREE PHYSIOLOGY
Results
Variations of K+and Na+in poplar roots under LT NaCl stress
In this study,X-ray microanalysis(SEM-EDAX)was used to detect Na+and K+levels in root cross sections.Control P.euphratica plants have typically higher Na+but lower K+than P.popularis(Figure1A and B).The LT salinity (50mM NaCl,3weeks)caused a signi?cant rise of Na+, which paralleled a marked K+reduction in the two species; however,a more pronounced e?ect was found in P.popularis(Figure1A and B).As a result,salt-induced reduction of K+/Na+was greater in P.popularis(93%) than in P.euphratica(69%)(Figure1C).
Ca2+supplement(10mM)signi?cantly reduced the ele-vation of Na+but simultaneously decreased K+loss in NaCl-stressed P.popularis(Figure1A and B),resulting in a less declined K+/Na+as compared to stressed plants without Ca2+application(Figure1C).However,Ca2+ did not signi?cantly change the levels of K+and Na+ (Figure1A and B)or K+/Na+ratios in salinized P.euphratica roots(Figure1C).
Steady ion?uxes under LT salinity
By means of the SIET,steady?ux pro?les of K+,Na+and H+were measured along the root axes at the apex(200–2000l m from the root tip at an interval of300l m)and mature regions(10–12mm from the root tip at an interval of500l m),respectively.
K+?uxes Salinity caused a signi?cant net K+e?ux in the root apex of P.popularis,although the?ux rate declined with increased duration of salinity exposure(Figure2).
CALCIUM MEDIATES ROOT K+/Na+HOMEOSTASIS IN POPLAR SPECIES5 TREE PHYSIOLOGY ONLINE at https://www.doczj.com/doc/4115408526.html,
It is noteworthy that Ca2+introduction markedly reduced the salt-induced K+e?ux on day7and14,respectively (Figure2).In contrast to P.popularis,P.euphratica main-tained a stable K+?ux in apical regions and was not altered by salt stress(Figure2).In the3-week salinity, K+?uxes remained at lower levels in mature roots of the two species,irrespective of treatments(Figure2).
Na+?uxes Net Na+e?ux in P.euphratica was signi?-cantly increased by salinity in both mature and apical regions, with the e?ect more pronounced in the apex (Figure2).Ca2+application enhanced the salt-induced Na+e?ux in P.euphratica roots,but only after21days of stress(Figure2).Similarly,Na+e?ux in stressed P.popularis was enhanced by Ca2+treatment,although non-Ca2+-treated roots(both apical and mature regions) did not show an evident Na+e?ux over3weeks of salinity (Figure2).
H+?uxes NaCl signi?cantly increased H+in?ux in P.euphratica roots,although mature roots typically had a lower?ux rate than the apex during the period of salt exposure(Figure2).Ca2+treatment increased H+in?ux in both the apical and mature regions of P.euphratica roots,only at day21(Figure2).This was also observed in P.popularis roots,despite a lower?ux exhibited by stressed plants of this species(Figure2).
E?ects of Ca2+on Na+/H+exchange After being sub-jected to a prolonged salt exposure,a signi?cantly positive correlation between Na+e?ux and H+in?ux was shown in P.euphratica roots(both the apical and mature roots) (Figure3A),but was absent in P.popularis roots (Figure3C).Ca2+application markedly enhanced the Na+/H+exchange in the two species,with a more pro-nounced e?ect in P.popularis roots(Figure3B and D). Transient kinetics upon NaCl shock
Transient K+and H+kinetics response to SS was exam-ined in both apical and mature regions,which were about 0.5and12mm from the root tip,respectively.E?ects of NaCl on Na+kinetics were not examined due to the declined S/N of Na+LIX in a measuring bath containing higher Na+(Sun et al.2009).
6SUN ET AL.
TREE PHYSIOLOGY
K+kinetics When exposed to a SS,root K+e?ux in apical regions and mature roots showed a biphasic pattern, with a rapid increase to peaking levels after the onset of salt exposure,then followed by a gradual decrease and?nally reaching a stable level(Figure4).In comparison,salt-shocked P.popularis showed a greater K+e?ux than P.eu-phratica in both mature and apical zones over the recording period(ca.40min)(Figure4).
Pharmacological experiments upon SS were conducted at the root apex.As shown in Figure5,transient K+kinetics response to NaCl was mediated by TEA(K+channel blocker),sodium orthovanadate(the inhibitor of PM H+-ATPase)and Ca2+,but di?erent e?ects were observed. TEA+and Ca2+signi?cantly decreased K+e?ux in shocked roots of the two species(Figure5A,B,E and F); in contrast,sodium vanadate accelerated K+e?ux in both species,as compared to non-vanadate-pretreated roots (Figure5C and D).
H+kinetics For P.euphratica roots,the pattern of H+?ux in apical regions signi?cantly di?ers from mature zones,regardless of treatments.Root apex showed a steady H+in?ux under no-salt conditions,but H+markedly shifted towards e?ux upon NaCl shock with a peaking level of180pmol cmà2sà1after20min of salt addition (Figure6).In contrast,mature roots exhibited a steady H+e?ux,but it was signi?cantly reduced by the NaCl shock(Figure6).Unlike P.euphratica,NaCl shock did not signi?cantly change the H+?ux in P.popularis roots, although mature zones had a larger H+in?ux than apical regions(Figure6).
E?ect of sodium vanadate on NaCl-induced H+kinetics was examined at the root apex of P.euphratica.As shown in Figure7,the enhanced H+e?ux that was caused by SS and the corresponding acidi?cation were both signi?cantly inhibited by the pretreatment of sodium vanadate. Discussion
Species-speci?c di?erence in controlling K+/Na+ homeostasis under NaCl
Results from X-ray microanalysis show that LT-stressed P.euphratica roots have a greater capacity to retain K+/ Na+homeostasis than the salt-sensitive species,P.popularis (Figure1).This is consistent with our previous studies at whole-plant and tissue levels that were measured with atomic absorption?ame photometry(Chen et al.2001,2002a, 2002b,2003).In this study,SIET data indicate that the main-tenance of K+/Na+homeostasis in P.euphratica roots accounted for(1)the lower K+e?ux and(2)the greater Na+extrusion under NaCl stress.
LT-stressed P.euphratica roots(apical regions)showed a lower K+e?ux as compared to P.popularis(Figure2).The same trend was found at both mature and apical regions of salt-shocked P.euphratica roots(Figure4).Similarly,salt-tolerant cultivars of barley and wheat exhibit a smaller K+e?ux than salt-sensitive ones under saline conditions (Chen et al.2005,2007,Cuin et al.2008).However,higher ?ux rates were detected at mature roots of these crop spe-cies,which is di?erent from poplar species in which a larger ?ux was usually found at the root apex(Figures2and4). The transient K+e?ux caused by the SS was signi?cantly reduced by the K+channel blocker(TEA)but enhanced by the inhibitor of PM H+-ATPase(sodium orthovanadate) in apical regions of the two tested species(Figure5A–D). This suggests that NaCl-induced K+e?ux is mediated by the depolarization-activated channels, e.g.,KORCs and NSCCs(Shabala et al.2005,2006,Chen et al.2007, Shabala and Cuin2008).The marked di?erences in K+ e?ux upon NaCl shock between the two poplar species likely result from the magnitude of membrane depolariza-tion,which is largely dependent on the activity of PM H+-ATPase(Chen et al.2007).The apex of salt-shocked P.euphratica displayed a pronounced H+e?ux(Figure6). Mature roots of P.euphratica had a steady H+e?ux, although it was signi?cantly reduced by the NaCl shock(Figure6).Collectively,the larger H+e?ux at both mature and apical regions indicates a highly activated
CALCIUM MEDIATES ROOT K+/Na+HOMEOSTASIS IN POPLAR SPECIES7 TREE PHYSIOLOGY ONLINE at https://www.doczj.com/doc/4115408526.html,
PM H+-ATPase in salt-shocked P.euphratica roots (Figure7).Therefore,salinized P.euphratica roots retained a higher H+-pumping activity,which leads to repolariza-tion or hyperpolarization of the PM and decreases the K+loss through DA-KORCs and DA-NSCCs.The inhibi-tion of H+pumping on K+loss could also be applied to LT-stressed P.euphratica roots.By means of the cytochem-ical technique,we found the up-regulated PM H+-ATPase activity in P.euphratica roots after a prolonged exposure to NaCl stress(our unpublished data),which presumably con-tributes to hyperpolarizing the PM and restricting the depo-larization-dependent K+e?ux.
LT-stressed P.euphratica roots(apex and mature zones)retained a greater capacity for Na+exclusion than P.popularis(Figure2),which is consistent with our previous report(Sun et al.2009).The evident correlation between Na+(net e?ux)and H+(net in?ux)suggests that the Na+extrusion in P.euphratica roots is mainly the result of Na+/H+exchange(Figure3).Na+/H+antiporters of P.euphratica,e.g.,PeNhaD1and PeSOS1,may play an important role to exclude Na+under NaCl stress(Ottow et al.2005b,Chen2007,Wu et al.2007).By means of A?ymetrix poplar gene chips,microarray analyses show that P.euphratica retains a typically higher transcript abun-dance of the genes encoding Na+/H+antiporters,e.g., PeSOS1,as compared to P.popularis(our unpublished data).Our previous report has shown that the Na+/H+ exchange in root cells of P.euphratica is correlated to the activity of PM H+-ATPase(Sun et al.2009).In this study, NaCl shock markedly increased the H+e?ux in the apex
8SUN ET AL.
TREE PHYSIOLOGY
and caused a corresponding acidi?cation,but all of them were inhibited by the inhibitor of PM H+-ATPase,sodium orthovanadate(Figure7).Given these results,we conclude
that SS rapidly activates PM H+-ATPase,thus creating an acidic environment,which is favourable for the Na+/H+ exchange across the PM.Ottow et al.(2005b)have con-?rmed that PeNhaD1is strictly pH dependent and func-tions in acidic conditions, e.g.,pH 5.5.Similar results were obtained in our studies with root-derived protoplasts isolated from LT-stressed P.euphratica plants(Sun et al. 2009).Accordingly,in the LT experiment,the increased activity of Na+/H+antiport(extruding Na+from the cell in exchange for H+in?ux)in NaCl-treated P.euphratica roots indicates that the PM H+-ATPase is able to pump protons and maintain electrochemical H+gradients,thus promoting the secondary Na+/H+antiport(Blumwald et al.2000,Zhu2003).
Compared to P.euphratica,P.popularis roots were unable to restrict the buildup of Na+but displayed a greater K+reduction,leading to perturbations of K+/Na+homeo-stasis after long periods of salinity(Figure1).The inability to retain K+/Na+homeostasis in salinized P.popularis is likely due to(1)the lower H+-pumping activity (Figure6),which was unable to hyperpolarize or to repolar-ize the PM,thus not able to limit the K+e?ux through DA-KORC and DA-NSCCs and(2)the weak Na+/H+antiport system in the PM(Figures2and3C),which is insu?cient to exclude the entry of Na+,likely through VI-NSCCs (Maathuis and Sanders2001,Demidchik and Tester2002, Demidchik et al.2002,White and Davenport2002,Tester and Davenport2003,Maathuis2006,Shabala et al.2006). The correlation between Ca2+and K+/Na+homeostasis
Ca2+application to P.popularis roots was found to be favourable for maintaining K+/Na+homeostasis over 3weeks of salinity(Figure1).As evident by steady SIET recording,K+e?ux in the root apex of LT-stressed P.popularis was markedly reduced by Ca2+supplement (Figure2).Similarly,transient kinetics measurements showed that Ca2+e?ectively restricted the NaCl-induced K+e?ux in the two tested species(Figure5E and F). The reduction of K+e?ux likely results from the inhibitory e?ect of Ca2+on DA-KORC and NSCCs that mediate K+e?ux under saline conditions(Shabala et al.2006).
CALCIUM MEDIATES ROOT K+/Na+HOMEOSTASIS IN POPLAR SPECIES9 TREE PHYSIOLOGY ONLINE at https://www.doczj.com/doc/4115408526.html,
It is noteworthy that the net Na+e?ux was signi?cantly enhanced by Ca2+in LT-stressed roots(both mature and apical zones)(Figure2).This is mainly due to the inhibition of Na+entry as it has been shown repeatedly that Ca2+ treatment inhibits Na+in?ux via NSCCs(Demidchik et al.2002,Tester and Davenport2003;Demidchik and Maathuis2007).At present,we cannot conclude that Ca2+promotes Na+/H+exchange even when the apparent increase in Na+e?ux with Ca2+treatment was found in poplar roots(Figures2and3),because our SIET data only show a net?ux of the target element across the PM,instead of the unidirectional?ux.
Conclusion
In conclusion,P.euphratica roots display a higher capacity to retain K+/Na+homeostasis over a long period of salin-ity,resulting from the lower K+e?ux and a higher Na+ exclusion.Pharmacological evidence reveals that the K+ e?ux caused by NaCl is mediated by depolarization-activated KORCs and NSCCs.The correlation between H+and Na+?uxes in LT-stressed P.euphratica roots indi-cates that the Na+extrusion is mainly the result of Na+/ H+antiport across the PM.Moreover,the greater ability to control K+/Na+homeostasis in P.euphratica roots is associated with the H+-pumping activity under salt stress. In addition to providing an electrochemical H+gradient for the Na+/H+exchange,H+pumps repolarize the PM,thus reducing the Na+in?ux via NSCCs and simulta-neously decreasing K+loss through DA-KORCs and DA-NSCCs.In comparison,P.popularis was unable to restrict K+e?ux and its Na+/H+antiport system was insu?cient to exclude Na+,leading to perturbations of K+/Na+homeostasis after a LT salinity.Ca2+application e?ectively limited K+e?ux in both SS-and LT-stressed plants,presumably resulting from the inhibition of Ca2+on DA-KORC and NSCCs.Ca2+addition resulted in an apparent Na+e?ux in LT-stressed roots,which is likely the result of Na+in?ux inhibition.Therefore,we conclude that the exogenous Ca2+enables the two poplar species, especially the salt-sensitive P.popularis,to retain K+/ Na+homeostasis in roots after a prolonged exposure to salinity.
Acknowledgments
The research was supported jointly by the National Natural Science Foundation of China(30430430and30872005),the HI-TECH Research and Development Program of China(863Pro-gram,2006AA10Z131),Foundation for the Supervisors of Beijing Excellent Doctoral Dissertation(YB20081002201),Foundation for the Authors of National Excellent Doctoral Dissertation of P.R.China(200152),the Teaching and Research Award Program for Outstanding Young Teachers in Higher Education Institution of Ministry of Education(MOE),PRC(2002-323),Key Project of MOE,PRC(2009-84)and the Natural Science Foundation of Hubei Province(2007ABB003).
References
Apse,M.P.and E.Blumwald.2007.Na+transport in plants.
FEBS Lett.581:2247–2254.
Apse,M.P.,G.S.Aharon,W.A.Snedden and E.Blumwald.
1999.Salt tolerance conferred by overexpression of a vacuolar Na+/H+antiporter in Arabidopsis.Science285:1256–1258. Arshi,A.,M.Z.Abdin and M.Iqbal.2005.Ameliorative e?ects of CaCl2on growth,ionic relations,and praline content of senna under salinity stress.J.Plant Nutr.28:101–125. Blumwald, E.,G.S.Aharon and M.P.Apse.2000.Sodium transport in plant cells.Biochim.Biophys.Acta1465: 140–151.
Caines,A.M.and C.Shennan.1999.Interactive e?ects of Ca2+ and NaCl salinity on the growth of two tomato genotypes di?ering in Ca2+use e?ciency.Plant Physiol.Biochem.
37:569–576.
Chen, C.X.2007.PeNhaD1gene transformation and salt resistance of transgenic Populus tomentosa.Ph.D.Thesis.
Beijing Forestry University,Beijing,People’s Republic of China(in Chinese).
Chen,S.L.,E.Fritz,S.S.Wang,A.Hu ttermann,Q.L.Liu and X.N.Jiang.2000.Cellular distribution of ions in salt-stressed cells of Populus euphratica and P.tomentosa.For.Stud.China 2:8–16.
Chen,S.,J.Li,S.Wang,A.Hu ttermann and A.Altman.2001.
Salt,nutrient uptake and transport,and ABA of Populus euphratica;a hybrid in response to increasing soil NaCl.Trees 15:186–194.
Chen,S.,J.Li,E.Fritz,S.Wang and A.Hu ttermann.2002a.
Sodium and chloride distribution in roots and transport in three poplar genotypes under increasing NaCl stress.For.
Ecol.Manag.168:217–230.
Chen,S.L.,J.K.Li,W.L.Yin,S.S.Wang,E.Fritz,A.Polle and
A.Hu ttermann.2002b.Tissue and cellular K+,Ca2+and
Mg2+of poplar under saline conditions.J.Beijing For.Univ.
24:84–88(in Chinese with English abstract).
Chen,S.,J.Li,S.Wang, E.Fritz, A.Hu ttermann and
A.Altman.2003.E?ects of NaCl on shoot growth,transpi-
ration,ion compartmentation,and transport in regenerated plants of Populus euphratica and Populus tomentosa.Can.
J.For.Res.33:967–975.
Chen,Z.,I.Newman,M.Zhou,N.Mendham,G.Zhang and S.Shabala.2005.Screening plants for salt tolerance by measuring K+?ux:a case study for barley.Plant Cell Environ.28:1230–1246.
Chen,Z.,I.I.Pottosin,T.A.Cuin et al.2007.Root plasma membrane transporters controlling K+/Na+homeostasis in salt stressed barley.Plant Physiol.145:1714–1725.
Cuin,T.A.,S.A.Betts,R.Chalmandrier and S.Shabala.2008.
A root’s ability to retain K+correlates with salt tolerance in
wheat.J.Exp.Bot.59:2697–2706.
Demidchik,V.and F.J.M.Maathuis.2007.Physiological roles of nonselective cation channels in plants:from salt stress to signalling and development.New Phytol.175:387–404. Demidchik,V.and M.Tester.2002.Sodium?uxes through nonselective cation channels in the plasma membrane of protoplasts from Arabidopsis roots.Plant Physiol.128: 379–387.
10SUN ET AL.
TREE PHYSIOLOGY
Demidchik,V.,R.J.Davenport and M.Tester.2002.Nonselec-tive cation channels in plants.Annu.Rev.Plant Biol.53: 67–107.
Escalante-Pe rez,M.,https://www.doczj.com/doc/4115408526.html,utner,U.Nehls et al.2009.Salt stress a?ects xylem di?erentiation of grey poplar(Populus·canes-cens).Planta229:299–309.
Fukuda,A.,A.Nakamura,A.Tagiri,H.Tanaka,A.Miyao,H.
Hirochica and Y.Tanaka.2004.Function,intracellular localization and the importance in salt tolerance of a vacuolar Na+/H+antiporter from rice.Plant Cell Physiol.45:146–159. Hasegawa,P.M.,R.A.Bressan,J.K.Zhu and J.H.Bohnert.
2000.Plant cellular and molecular responses to high salinity.
Annu.Rev.Plant Physiol.Plant Mol.Biol.51:463–499. Kochian,L.V.,J.E.Sha?,W.M.Ku htreiber,L.F.Ja?e and W.J.
https://www.doczj.com/doc/4115408526.html,e of an extracellular,ion-selective,vibrating microelectrode system for the quanti?cation of K+,H+,and Ca2+?uxes in maize roots and maize suspension cells.Planta 188:601–610.
Ku htreiber,W.M.and L.F.Ja?e.1990.Detection of extracel-lular calcium gradients with a calcium-speci?c vibrating electrode.J.Cell Biol.110:1565–1573.
Kunkel,J.G.,S.Cordeiro,Y.Xu,A.M.Shipley and J.A.Feijo.
2006.The use of non-invasive ion-selective microelectrode techniques for the study of plant development.In Plant Electrophysiology–Theory and Methods.Ed.A.G.Volkov.
Springer,Berlin/Heidelberg,Germany,pp109–137.
Liu,J.P.and J.K.Zhu.1997.An Arabidopsis mutant that requires increased calcium for potassium nutrition and salt https://www.doczj.com/doc/4115408526.html,A94:14960–14964. Lu,P.P.,J.Hu,S.L.Chen,X.Shen,W.L.Yin,Y.H.Chen,Y.R.
Sun and Z.M.Hu.2007.Function of the putative Na+/H+ antiporter gene PeNhaD1from salt-resistant Populus euphra-tica Oliv.J.Plant Physiol.Mol.Biol.33:173–178(in Chinese with English abstract).
Ma,T.J.,Q.L.Liu,Z.Li and X.J.Zhang.2002.Tonoplast H+-ATPase in response to salt stress in Populus euphratica cell suspensions.Plant Sci.163:499–505.
Maathuis,F.J.M.2006.The role of monovalent cation trans-porters in plant responses to salinity.J.Exp.Bot.57: 1137–1147.
Maathuis,F.J.M.and A.Amtmann.1999.K+nutrition and Na+toxicity:the basis of cellular K+/Na+ratios.Ann.Bot.
84:123–133.
Maathuis, F.J.M.and D.Sanders.2001.Sodium uptake in Arabidopsis thaliana roots is regulated by cyclic nucleotides.
Plant Physiol.127:1617–1625.
Munns,R.and M.Tester.2008.Mechanisms of salt tolerance.
Annu.Rev.Plant Biol.59:651–681.
Ohta,M.,Y.Hayashi,A.Nakashima,A.Hamada,A.Tanaka, T.Nakamura and T.Hayakawa.2002.Introduction of a Na+/H+antiporter gene from Atriplex gmelini confers salt tolerance to rice.FEBS Lett.532:279–282.
Ottow,E.A.,M.Brinker,T.Teichmann,E.Fritz,W.Kaiser, M.Brosche,J.Kangasja rvi,X.Jiang and A.Polle.2005a.
Populus euphratica displays apoplastic sodium accumulation, osmotic adjustment by decreases in calcium and soluble carbohydrates,and develops leaf succulence under salt stress.
Plant Physiol.139:1762–1772.
Ottow,E.A.,A.Polle,M.Brosche,J.Kangasja rvi,P.Dibrov,
C.Zo rb and T.Teichmann.2005b.Molecular characteriza-
tion of PeNhaD1:the?rst member of the NhaD Na+/H+antiporter family of plant origin.Plant Mol.
Biol.58:73–86.Parks,G.E.,M.A.Dietrich and K.S.Schumaker.2002.Increased vacuolar Na+/H+exchange activity in Salicornia bigelovii Torr.in response to NaCl.J.Exp.Bot.53:1055–1065. Renault,S.2005.Response of red-osier dogwood(Cornus stolonifera)seedlings to sodium sulphate salinity:e?ects of supplemental calcium.Physiol.Plant123:75–81.
Shabala,S.2000.Ionic and osmotic components of salt stress speci?cally modulate net ion?uxes from bean leaf mesophyll.
Plant Cell Environ.23:825–837.
Shabala,S.and T.A.Cuin.2008.Cellular mechanisms of potassium transport in plants.Physiol.Plant.133:651–669. Shabala,S.,L.Shabala and E.van Volkenburgh.2003.E?ect of calcium on root development and root ion?uxes in salinised barley seedlings.Funct.Plant Biol.30:507–514.
Shabala,L.,T.A.Cuin,I.Newman and S.Shabala.2005.
Salinity-induced ion?ux patterns from the excised roots of Arabidopsis sos mutants.Planta222:1041–1050.
Shabala,S.,V.Demidchik,L.Shabala,T.A.Cuin,S.J.Smith,
https://www.doczj.com/doc/4115408526.html,ler,J.M.Davies and I.A.Newman.2006.Extracel-
lular Ca2+ameliorates NaCl-induced K+loss from Arabid-opsis root and leaf cells by controlling plasma membrane K+-permeable channels.Plant Physiol.141:1653–1665. Shi,H.,M.Ishitani, C.Kim and J.K.Zhu.2000.The Arabidopsis thaliana salt tolerance gene SOS1encodes a putative Na+/H+https://www.doczj.com/doc/4115408526.html,A 97:6896–6901.
Shi,H.,B.H.Lee,S.J.Wu and J.K.Zhu.2003.Overexpression of a plasma membrane Na+/H+antiporter gene improves salt tolerance in Arabidopsis thaliana.Nat.Biotechnol.21: 81–85.
Sun,J.,S.Chen,S.Dai et al.2009.NaCl-induced alternations of cellular and tissue ion?uxes in roots of salt-resistant and salt-sensitive poplar species.Plant Physiol.149:1141–1153. Tester,M.and R.Davenport.2003.Na+tolerance and Na+ transport in higher plants.Ann.Bot.91:503–527. Vincent,P.,M.Chua,F.Nogue,A.Fairbrother,H.Mekeel, Y.Xu,N.Allen,T.N.Bibikova,S.Gilroy and V.A.
Bankaitis.2005.A sec14p-nodulin domain phosphatidylino-sitol transfer protein polarizes membrane growth of Arabid-opsis thaliana root hairs.J.Cell Biol.168:801–812.
Wang,R.,S.Chen,H.Ma,L.Liu,H.Li,H.Weng,Z.Hao and S.Yang.2006.Genotypic di?erences in antioxidative stress and salt tolerance of three poplars under salt stress.Front.
For.China1:82–88.
Wang,R.,S.Chen,L.Deng,E.Fritz,A.Hu ttermann and
A.Polle.2007.Leaf photosynthesis,?uorescence response to
salinity and the relevance to chloroplast salt compartmentation and anti-oxidative stress in two poplars.Trees21:581–591. Wang,R.,S.Chen,X.Zhou et al.2008.Ionic homeostasis and reactive oxygen species control in leaves and xylem sap of two poplars subjected to NaCl stress.Tree Physiol.28:947–957. White,P.J.and R.J.Davenport.2002.The voltage-independent cation channel in the plasma membrane of wheat roots is permeable to divalent cations and may be involved in cytosolic Ca2+homeostasis.Plant Physiol.130:1386–1395. Wu,Y.,N.Ding,X.Zhao,M.Zhao,Z.Chang,J.Liu and L.Zhang.2007.Molecular characterization of PeSOS1:the putative Na+/H+antiporter of Populus euphratica.Plant Mol.Biol.65:1–11.
Xu,Y.,T.Sun and L.P.Yin.2006.Application of non-invasive microsensing system to simultaneously measure both H+and O2?uxes around the pollen tube.J.Integr.Plant Biol.48: 823–831.
CALCIUM MEDIATES ROOT K+/Na+HOMEOSTASIS IN POPLAR SPECIES11 TREE PHYSIOLOGY ONLINE at https://www.doczj.com/doc/4115408526.html,
Yang,Y.L.,F.Zhang,M.Zhao,L.An,L.Zhang and N.Chen.
2007a.Properties of plasma membrane H+-ATPase in salt-treated Populus euphratica callus.Plant Cell Rep.26:229–235. Yang,Y.Q.,L.Hu,X.Chen,E.A.Ottow,A.Polle and X.Jiang.
2007b.A novel method to quantify H+-ATPase-dependent Na+transport across plasma membrane vesicles.Biochim.
Biophys.Acta1768:2078–2088.
Zhang,F.,Y.Wang,Y.L.Yang,H.Wu,D.Wang and J.Q.Liu.
2007.Involvement of hydrogen peroxide and nitric oxide in
salt resistance in the calluses from Populus euphratica.Plant Cell Environ.30:775–785.
Zhu,J.K.2001.Plant salt tolerance.Trends Plant Sci.6:66–71. Zhu,J.K.2003.Regulation of ion homeostasis under salt stress.
Curr.Opin.Plant Biol.6:1–5.
Zonia,L.,S.Cordeiro,J.Tupy and J.A.Feijo.2002.Oscillatory chloride e?ux at the pollen tube apex has a role in growth and cell volume regulation and is targeted by inositol-3,4,5,6-tetrakisphosphate.Plant Cell14:2233–2249.
12SUN ET AL.
TREE PHYSIOLOGY
钙钛矿型催化剂La1-x Ce x CoO3对一氧化氮的氧化催化研究 摘要 本文介绍了在钙钛矿氧化物中的NO的氧化性能的研究La1-x Ce x CoO3 (x = 0, 0.05, 0.1, 0.2, 0.3, 0.4)通过柠檬酸盐法合成钙钛矿型氧化物并以XRD, BETand XPS为特征。当使用铈替代催化剂时催化活性显著增强，并取得了当x=0.2时活性最大，但X越大活性会降低。分析表明，表面上吸附的氧对NO氧化成NO2起着重要的作用。在室温下，NO和O2共吸附层之下的表面化合物，通过红外光谱和TPD实验进行了研究。有三个品种形成在表明上分别是：桥接硝酸盐，次硝酸和单齿硝酸盐。热稳定性的顺序为：单齿硝酸盐> 次硝酸>桥接硝酸盐。其中，仅单齿硝酸盐在300摄氏度以上会分解，解除吸附变为NO2进入气相。当Ce的加入，单齿硝酸盐解脱吸附的温度变低，另外两个品种的吸附减少。这可能与表面上的钴的氧化状态有关。通过对表征结果和催化活性的数据的结合分析显示，大量吸附的氧，表面上少量的非活性化合物和较低的NO2接触吸附温度会有利于NO的氧化。 ＃2007爱思唯尔B.V.保留所有权利。 1 介绍 对NO x催化消除的广泛研究已进行了多年。然而，除去柴油发动机和过量氧气贫燃条件下的汽油发动机中的NO x仍然是一个挑战。在研制的几个NO X氧化环境转化的过程中NO2总是比NO更加受宠，例如NO x的储存和还原技术（NSR）[1]，为去除氮氧化物和烟尘的连续再生陷阱技术（CRT）[2]，选择性催化还原氮氧化物（SCR），尤其是某些N-所含物种如氨或尿素。[3-5]我们还发现，形成二氧化氮是在NO的SCR的碳氢化合物机制的重要一步[6.7]。一些研究人员也开发了几种更复杂的系统，例如'VHRO系统'（V= 对NO到NO2的氧化催化剂，H =水解催化剂，R = SCR催化剂，O =对NH3的氧化催化剂）[5]和IAR法（在氧化和还原剂的还原催化剂之间加入）[8]。在这些系统中，它们都在NO的氧化添加还原剂之前设置一个预催化剂，使还原剂的效率得到显著改善。总之，在一氧化氮氧化为二氧化碳的过程中放置催化剂是使人非常感兴趣的。 铂基催化剂是现在最常用于NO氧化的催化剂。Despre′s Joe¨l等，观察到铂/二氧化硅（2.5重量％）可在300摄氏度时转换约80％的NO为NO2[9]。并且当铂
新型类钙钛矿电极材料的设计和性能研究固体氧化物燃料电池(SOFC)是一种转换效率高且环境友好的能源转换设备,能够将燃料中的化学能高效的转换为电能,而其电化学逆过程(即固体氧化物电解电池,SOEC)则可以将电能转换为化学能储存在燃料中。SOFC-SOEC联用可以有效地解决风能、太阳能、潮汐能等清洁发电设备的输出波动问题,实现并网。 但是目前SOFC的商业化应用仍遇到很多困难,最重要的就是高性能电极材料的开发,包括可用于碳氢燃料的阳极材料以及高催化活性和稳定性的阴极材料等。为进一步发展高性能、稳定的电极材料,以提高电池的电化学性能和运行稳定性,本文主要进行以下几下研究：(1)新型质子型固体氧化物燃料电池(P-SOFC)的阴极材料-Sr3Fe207-δ的制备、性能和应用电化学性能研究；(2)Co和La掺杂对Sr3Fe2O7-δ性能的影响及其作为P-SOEC空气极的可行性研究； (3)Sr2Fe1.5Mo0.5O6-δ(SFM)单相陶瓷电极在可逆固体氧化物电池中的离子浸渍法制备及应用性能研究；(4)基于NiTiO3阳极重整层和Co2TiO4新阳极材料的单电池在碳氢燃料中的电化学行为研究。 论文的结果如下：第一章：简单介绍了SOFC的研究背景、运行原理和各组件的发展现状。重点阐述了SOFC中电极材料的发展现状和未来商业化要求对于电极材料的要求,提出本论文的研究方向和内容。 第二章：针对P-SOFC的阴极电化学反应过程,设计并研究了具有类钙钛矿R-P结构的Sr3Fe207-δ单相阴极材料。结果表明：(1) Sr3Fe207-δ (SFO)具有良好的电子电导率和氧离子电导率,800℃下氧渗透率为6.06*10-8molcm-2s-1,电子电导率最高可达60Scm-1。 (2)DFT理论计算表明其特殊的R-P层状结构使SFO具有很低的质子形成能
硅钙板吊顶安装施工方案 一、材料准备 轻钢龙骨、配件、吊杆、膨胀螺栓、硅钙板等，进场检验合格，有出厂合格证及材料质量证明。 二、机具准备 型材切割机、电动曲线锯、手电钻、电锤、自攻螺钉钻、手提电动砂纸机等。 三、作业条件 1 在所要吊顶的范围内，机电安装均已施工完毕，各种管线均已试压合格，已经过隐蔽验收。 2 已确定灯位、通风口及各种照明孔口的位置。 3 顶棚罩面板安装前，应作完墙、地湿作业工程项目。 4 搭好顶棚施工操作平台架子。 5 轻钢骨架顶棚在大面积施工前，应做样板，对顶棚的起拱度、灯糟、窗帘盒、通风口等处进行构造处理，经鉴定后再大面积施工。 四、施工工艺 1 工艺流程 弹标高水平、划分龙骨分档线→固定吊杆挂件→安装边龙骨→安装主龙骨→安装大龙骨→安装次龙骨→罩面板安装 2 弹标高水平、划分龙骨分档线：用水准仪在房间内每个墙角上抄出水平点（若墙体较长，中间也应适当抄出几点）弹出水准线，从水准备线量至吊顶高度：3800mm，用粉线沿墙弹出吊顶次龙骨的下皮线。同时，按吊顶平面图，在混凝土顶板弱出主龙骨的位置线。主龙骨宜平行房间长向布置，一般从吊顶中心向两边分。主龙骨及吊杆间距为1000mm。如遇到梁和管道固定点大于1000ｍｍ，增加吊杆固定点，且用5#角钢加强，间距2米。 3 固定吊挂杆件：采用膨胀螺栓固定吊挂件。吊杆采用10号镀锌低碳钢丝吊杆，并设置反向支撑，反向支撑采用5#角钢，间距3米-4米。吊杆用膨胀螺栓固定在楼板上，用冲击电锤打孔，孔径应稍大于膨胀螺栓的直径。吊杆距主龙骨端部距离不得超过300mm，否则应增加吊杆。灯具、风口、及检修口等应设附加吊杆。大于3kg的重型灯具、电扇及其他重型设备严禁安装在吊顶工程的龙骨上，应另设吊挂件与结构连接。 4 安装边龙骨：边龙骨安装应按设计标高要求弹线，采用L形镀锌次龙骨立放，砖砌墙用自攻螺丝固定在预埋的木楔子上，木楔子应做防腐处理，如为混凝土墙面可用射钉固定，射钉间距不应大于吊顶次龙骨间距。 5 安装主龙骨：主龙骨用CB38主龙骨，间距为1000mm。主龙骨应起拱，起拱高度为房间短向跨度的1/500。主龙骨的接头应采用对接，相邻龙骨的对接接头要相互错开。主龙骨挂好后应调平。；走廊内主龙骨沿走廊短方向排布。 6 安装次龙骨：次龙骨采用TB24*38轻钢龙骨，间距为60mm，次龙骨应紧贴主龙骨。用
目录 第1章绪论 (1) 1.1 磁电阻效应 (1) 1.2 巨磁电阻材料的应用及研究进展 (2) 1.2.1 巨磁电阻材料的应用 (2) 1.2.2 巨磁电阻材料的现状与展望 (2) 1.3 双钙钛矿型氧化物介绍 (3) 1.3.1 双钙钛矿型氧化物的结构 (3) 1.3.2 双钙钛矿型氧化物的电磁性质 (4) 1.3.3 A位和B位取代对双钙钛矿型氧化物电磁性质的影响 (9) 1.3.4 双钙钛矿型氧化物的制备方法 (10) 1.4 本论文的研究动机以及研究内容 (12) 第2章实验理论、样品制备、表征手段 (13) 2.1 实验理论 (13) 2.1.1 Jahn-Teller效应 (13) 2.1.2 极化子 (13) 2.1.3 容忍因子 (14) 2.1.4 超交换作用 (14) 2.1.5 双交换作用 (16) 2.1.6 电输运性质 (17) 2.2 样品的固相反应制备法 (18) 2.3 样品的表征手段 (20) 2.3.1 样品的晶体结构的XRD表征 (20) 2.3.2 样品磁性能的表征 (22) 2.3.3 样品电性能的表征 (23) 2.3.4 样品氮含量的测定 (24)
第3章Sr2FeMoO6-x N x系列样品的结构和性质的研究 (26) 3.1 概述 (26) 3.2 氮含量的测定 (26) 3.3 晶体结构的分析 (26) 3.4 样品磁性能的分析 (31) 3.5 样品电性能的分析 (34) 3.6小结 (37) 第4章Sr2-x Ce x FeMoO6-x N x系列样品的结构和性质的研究 (38) 4.1 概述 (38) 4.2 晶体结构的分析 (38) 4.3 样品磁性能的分析 (43) 4.4 样品电性能的分析 (46) 4.5 小结 (48) 第5章Sr2FeMoO6-x N x和Sr2-x Ce x FeMoO6-x N x样品结构性质对比 (49) 5.1 概述 (49) 5.2 晶体结构的比较 (49) 5.3 样品磁性能的比较 (51) 5.4 样品电性能的比较 (52) 第6章结论 (54) 参考文献 (55) 致谢 (60) 攻读学位期间取得的科研成果 (61)
轻钢龙骨石膏板吊顶施工工艺 1）、工艺流程 弹顶棚标高水平线→划龙骨分档线→专业管线安装→安装主龙骨→安装次龙骨→安装罩面板 2）、弹顶棚标高水平线，根据设计标高在各楼层的四周墙上弹水平控制线，弹线应清晰、准确。 3）、划龙骨分档线，按设计要求的主、次龙骨间距在已弹好的顶棚标高水平线上划龙骨分档线。 4）、安装主龙骨吊杆：为保证骨架的稳定，采用膨胀螺栓固定小角钢，角钢上焊Φ6吊杆。在弹好顶棚标高水平线及龙骨分档线后，确定吊杆下端头的标高，按主龙骨位置及吊杆间距固定吊杆，吊杆另一端焊Φ6螺栓丝杆，吊杆位置长度要准确适宜。吊杆不与专业管道接触。吊杆与专业管道发生冲突时，用型钢支架过渡。5）、龙骨安装：采用 50型龙骨或烤漆龙骨，龙骨中部起拱高度按房间短方向距离在1/200-1/300之间。主龙骨安装好后拉线校正，再安装次龙骨，次龙骨分档
必须按图纸要求进行，四边龙骨贴墙边，所有卡扣，配件位置要准确牢固。主龙骨悬挑端不大于300mm，主龙骨与专业管道和大型灯饰发生冲突时，先将主龙骨断开，再用型钢加固，必要时附加主龙骨。 6）、面层安装：龙骨安装完毕后让专业施工的管线安装完毕后再进 行面层的施工。面层为纸面石膏板或矿棉板，面层必须与龙骨连接牢固，平整，缝隙均匀、正确，各种留洞留设正确。 7）、刷防锈漆：轻钢骨架未做防腐处理的表面，如吊挂件、连接件、钉固附件等，在各工序安装前须刷防锈漆。 8）、与水、电、风等专业的配合： 吊顶工程是与水、电、风等专业交叉较多的施工项目之一，如果配合不好将不仅影响工程进度，而且还会造成材料浪费，所以必须协调好二者的关系。 首先吊顶施工必须在水管试压、保温，电管铺设、穿线完毕及风道安装，风机、调试完毕后进行。 电专业安装灯具及其它专业维修吊顶内的设施时必须有吊顶专业人员陪同，以免损坏或污染罩面板。
钙钛矿型复合氧化物材料 钙钛矿复合氧化物具有独特的晶体结构,尤其经掺杂后形成的晶体缺陷结构和性能,被应用或可被应用在固体燃料电池、固体电解质、传感器、高温加热材料、固体电阻器及替代贵金属的氧化还原催化剂等诸多领域,成为化学、物理和材料等领域的研究热点[1～4]。 1钙钛矿结构 钙钛矿型复合氧化物因具有天然钙钛矿(ＣａＴｉＯ3)结构而命名,与之相似的结构有正交、菱方、四方、单斜和三斜构型。标准钙钛矿结构中,Ａ2+和Ｏ2＿离子共同构成近似立方密堆积,Ａ离子有12个氧配位,氧离子同时有属于8个ＢＯ6八面体共享角,每个氧离子有6个阳离子(4Ａ～2Ｂ)连接,Ｂ2+离子有6个氧配位,占据着由氧离子形成的全部氧八面体空隙。钙钛矿结构的对称性较同种原子构成的最紧密堆积的对称性低,Ａ、Ｂ离子大小匹配。各离子半径间满足下列关系: 其中ＲＡ、ＲＢ、ＲＯ分别为Ａ离子、Ｂ离子和Ｏ2-离子的半径,但也存在不遵循该式的结构,可由Ｇｏｌｄｓｃｈｍｉｄｔ容忍因子ｔ来度量: 理想结构只在ｔ接近1或高温情况下出现,多数结构是它的不同畸变形式,这些畸变结构在高温时转变为立方结构,当ｔ在0.77～1.1,以钙钛矿存在;ｔ<0.77,以铁钛矿存在;ｔ>1.1时以方解石或文石型存在。 2钙钛矿型氧化物材料的研究进展 标准钙钛矿中Ａ或Ｂ位被其它金属离子取代或部分取代后可合成各种复合氧化物,形成阴离子缺陷或不同价态的Ｂ位离子,是一类性能优异、用途广泛的新型功能材料。 2.1固体氧化物燃料电池(ＳＯＦＣ)材料 钙钛矿氧化物燃料电池ＳＯＦＣ有以下优点:(1)全固态结构,不存在液态电解质所带来的腐蚀和电解液流失等问题;(2)无须使用贵金属电极,电池成本大大降低;(3)燃料适用范围广;(4)燃料可以在电池内部重整。通过电极材料中的掺杂来提高活性,优化碱锰电池的充放电性能(参见表1)。用含锰的钙钛矿氧化物作为碱性
硅钙板吊顶施工工艺及措施 一、施工准备 （一）作业条件 1、在所要吊顶的范围内，机电安装均已施工完毕，各种管线均已试压合格，已经隐蔽验收。 2、已确定灯位、通风口及各种照明孔口的位置。 3、顶棚罩面板安装前，应作完墙、地湿作业工程项目。 4、搭好顶棚施工操作平台架子。 5、轻钢骨架顶棚在大面积施工前，应做样板，对顶棚的起拱度、灯槽、窗帘盒、通风口等处进行构造处理，经鉴定后再大面积施工。 （二）材料准备 1、轻钢龙骨采用T 形龙骨，不上人。 2、轻钢骨架主件为中、小龙骨；配件有吊挂件、连接件、插接件。 3、零配件：通丝吊杆、膨胀螺栓、自攻螺钉、电焊机、双螺帽。 4、罩面板采用硅钙板。 5、所有材料进场检验合格且有出厂质量证明文件。 （三）施工机具 1、型材切割机、电动曲线锯、手电钻、电锤、自攻螺钉钻等。 二、操作工艺 （一）工艺流程 1、弹标高线一打孔下胀栓一安装主龙骨吊杆T安装烤漆主龙骨一安装烤漆副龙骨T 调平一安装硅钙板一装饰面清理 （二）主要操作工艺 1、弹线：根据设计标高，沿墙四周弹顶棚标高水平线，并沿水平标高线在墙四周画出龙骨分档位置线。其水平允许偏差± 5mm。 2、打孔下胀栓安装主龙骨吊杆，首先确定吊杆下端标高，安装吊杆，间距900—1200mm吊点分布均匀。 3、安装主龙骨、主龙骨间距900—1200mm主龙骨用配套的吊件安装，吊杆距主龙
骨边缘不大于300mm。 4、安装烤漆主龙骨、主龙骨间距为600mm烤漆主龙骨和吊杆之间用专用的吊件连接，安装后，整体调平。 5、安装烤漆副龙骨，副龙骨安装在烤漆主龙骨上，安装完后，拉通线整体调平。中间起拱高度按短向距离的1/200 起拱。 6、龙骨验收合格后安装硅钙板。硅钙板安装完成后需要进行板面清理。 三、质量要求： （一）主控项目 1、吊顶标高、尺寸、起拱和造型应符合设计要求。检验方法：观察；尺量检查。 2、饰面材料的材质、品种、规格、图案和颜色应符合设计要求。当饰面材料为玻璃板时，应使用安全玻璃或采取可靠的安全措施。检验方法：观察；检查产品合格证书、性能检测报告和进场验收记录。 3、饰面材料的安装应稳固严密。饰面材料与龙骨的搭接宽度应大于龙骨受力面宽度 的2/3 。 检验方法：观察；手扳检查；尺量检查。 4、吊杆、龙骨的材质、规格、安装间距及连接方式应符合设计要求。金属吊杆、龙骨应进行表面防腐处理；木龙骨应进行防腐、防火处理。检验方法：观察；尺量检查；检查产品合格证书进场验收记录和隐蔽工程验收记录。 5、明龙骨吊顶工程的吊杆和龙骨安装必须牢固。检验方法：手扳检查；检查隐蔽工程验收记录和施工记录。 （二）一般项目 1、饰面材料表面应洁净、色泽一致，不得有翘曲、裂缝及缺损。饰面板与明龙骨的搭接应平整、吻合，压条应平直、宽窄一致。检验方法：观察；尺量检查。 2、饰面板上的灯具、烟感器、喷淋头、风口篦子等设备的位置应合理、美观，与饰面板的交接应吻合、严密。检验方法：观察。 3、金属龙骨的接缝应平整、吻合、颜色一致、不得有划伤、擦伤等表面缺陷。木质
石膏板吊顶施工工艺 三、石膏板吊顶施工工艺 1、施工准备 1）原材料、半成品要求木料：木龙骨料应为烘干，无扭曲的红、白松树种，并按设计要求进行防火处理。木龙骨规格按设计要求，如设计无明确规定时，大龙骨规格为50mm×70mm或50mm×100mm；小龙骨规格为50mm×50mm 或40mm×50mm；木吊杆规格为50mm×50mm或40mm×40mm。罩面板材及压条。 纸面石膏板选用时严格掌握材质及规格标准。 其它材料φ6或φ8吊筋、膨胀螺栓、射钉、圆钉、角钢、扁钢、胶粘剂、木材防腐剂、防火剂、8号镀锌铁丝、防锈漆。 2）作业条件现浇楼板中按设计间距埋设φ6或φ8吊筋。当设计未做说明时，间距一般不大于1000mm。 墙为砌体时，应根据顶棚标高，在四周墙上预埋固定龙骨的木砖。 直接接触墙体的木龙骨，应预先刷防腐剂。 按工程不同防火等级和所处环境要求，对木龙骨进行喷涂防火涂料或置于防火涂料槽内浸渍处理。
顶棚内各种管线及通风管道均已安装完毕并经验收合格。各种灯具、报警器预留位置已经明确。 墙面及楼、地面湿作业和屋面防水已做完。 室内环境力求干燥，满足木龙骨吊顶作业的环境要求。 2、施工工艺 1）抄平弹线弹线包括：标高线、顶棚造型位置线、吊挂点布局线、大中型灯位线。 确定标高线：根据室内墙上+50cm水平线，用尺量至顶棚设计标高，在该点画出高度线，用一条塑料透明软管灌满水后，将软管的一端水平面对准墙面上的高度线。再将软管的另一端头水平面，在同侧墙面找出另一点，当软管内水平面静止时，画下该点的水平面位置，再将这两点连线，即得吊顶高度水平线。用同样方法在其它墙面做出高度水平线。操作时应注意，一个房间的基准高度点只用一个，各个墙的高度线测点共用。沿墙四周弹一道墨线，这条线便是吊顶四周的水平线，其偏差不能大于5mm。 确定造型位置线：对于较规则的建筑空间，其吊顶造型位置可先在一个墙面量出竖向距离，以此画出其它墙面的水平线，即得吊顶位
1 引言钙钛矿型氧化物(ABO3)由于独特的电、光、磁、特性是目前国内外材料研究领域中的热点。其在超导材料、固体电介质、传感器、高温加热材料固体电阻器及替代贵金属的氧化还原催化剂[1]等方面有广阔的潜在应用前景。铁酸镧（LaFeO3，LFO）是钙钛矿型氧化物中的一员[2]，是具有铁磁有序的绝缘介电材料。这类材料由于其电学特征敏感地依赖于其磁学有序，故在传感器和换能器等应用被寄予厚望。近年来，有关研究报道呈现快速增长趋势，主要集中在磁电耦合的机理性操作和具有优异性能材料与器件的制备与表征。薄膜的制备方法有很多，目前，主要采用四种方法：溶胶-凝胶法（(Sol-Gel）、脉冲激光沉积法、溅射法、分子束外延法。其中，溶胶-凝胶法具有独特优点而备受人们的关注，已发展成为不可缺少的制备方法。本文简要介绍了用溶胶凝胶法（Sol-gel）制备LFO薄膜的基本原理、工艺过程及其特点。 2 溶胶-凝胶法原理溶胶凝胶法（Sol-gel）是属于化学溶液法范畴，它是将有机或无机盐溶于共同的有机溶剂中以形成均匀澄清的前驱体溶液，并将其旋转沉积于衬底上，然后经过适当的热处理，得到薄膜的过程。其制备薄膜的基本过程是原材料、溶胶、凝胶、热处理、薄膜，其中溶胶的配置和热处理是影响薄膜质量的关键。根据原材料的不同，所涉及的化学途径也不一致[3-5]。根据原材料不同，Sol-gel法主要分为两类：水溶液和醇盐法，其中，醇盐法是较为常见的制备方法。以金属醇盐为前驱体，在溶胶配置过程涉及了复杂的化学反应，主要包括有水解和聚合反应[6] 。实际的水解反应和聚合反应进行的程度和速率，取决于金属原料、溶剂、浓度、催化剂、稳定剂、温度等因素，这是一个相当复杂的反应过程。要得到稳定的前驱溶液，必须控制好醇盐的水解活性。采用So-Gel法最大优点是容易配制稳定前驱体溶液，易于控制组元成分。故选择合适的原料来配置前驱溶液十分重要。
硅酸钙板施工 1、作业条件 1）吊顶工程在施工前应热悉施工图纸及设计说明。 2）吊顶工程在施工前应熟悉现场。 3）施工前应按设计要求对房间的净高、洞口标高和吊顶内的管道、设备及其支架的标高进行交接检验。 4）对吊顶内的管道、设备的安装及水管试压进行验收。 5）吊顶工程在施工中应做好各项施工记录，收集好各种有关文件。 6）材料进场验收记录和复验报告，技术交底记录。 7）板安装时室内湿度不宜大于70％以上。 2、施工工艺流程 吊顶标高弹水平线一划龙骨分档线一安装水电管线一安装主龙骨一安装次龙骨一安装罩面板一安装压条 3、操作工艺 1）弹线 用水准仪在房间内每个墙(柱)角上抄出水平点(若墙体较长，中间也应适当抄几个点)，弹出水准线(水准线距地面一般为500mm)，从水准线量至吊顶设计高度加上12mm(一层硅酸盖板的厚度)，用粉线沿墙(柱)弹出水准线，即为吊顶次龙骨的下皮线。同时，按吊顶平面图，在混凝土顶板弹出主龙骨的位置。主龙骨应从吊顶中心向两边分，最大间距为1000mm，并标出吊杆的固定点，吊杆的固定点间900～1000mm。如遇到梁和管道固定点大于设计和规程要求，应增加吊杆的固定点。 2）固定吊挂杆件 现浇钢筋混凝土板底预留直径8mm钢筋吊环双向中距小于1200；直径6mm钢筋吊环，双向中距小于1200吊杆上部与板底预留吊环固定；U型轻钢主龙骨CB38*12，中距小于1200找平后与钢筋吊杆固定；H型轻钢次龙骨LB20*20，中距600。制作好的吊杆应做防锈处理，吊杆用膨胀螺栓固定在楼板上，用冲击电锤打孔，孔径应稍大于膨胀螺栓的直径。 3）在梁上设置吊挂杆件 吊挂杆件应通直并有足够的承载能力。长时，必须搭接焊牢，焊缝要均匀饱满；吊杆距主龙骨端部距离不得超过300mm，否则应增加吊杆；吊顶灯具、风口及检修口等应设附加吊杆。 4）安装边龙骨 边龙骨的安装应按设计要求弹线，沿墙(柱)上的水平龙骨线把L形镀锌轻钢条用自攻螺丝固定在预埋木砖上；如为混凝土墙(柱)，可用射钉固定，射钉间距应不大于吊顶次龙骨的间距。 5）安装主龙骨 主龙骨应吊挂在吊杆上。主龙骨间距900一1000mm。主龙骨分为轻钢龙骨和T形龙骨。轻钢龙骨选用UC50中龙骨和UC38小龙骨。主龙骨应平行房间长向安装，同时应起拱，起拱高度为房间跨度的1／200～1／300。主龙骨的悬臂段不应大于300ram，否则应增加吊杆。主龙骨的接长应采取对接，相邻龙骨的对接接头要相互错开。主龙骨挂好后应基本调平。
第45卷第11期2017年11月 硅酸盐学报Vol. 45，No. 11 November，2017 JOURNAL OF THE CHINESE CERAMIC SOCIETY https://www.doczj.com/doc/4115408526.html, DOI：10.14062/j.issn.0454-5648.2017.11.16 新型双钙钛矿基对称固体氧化物燃料电池的制备及性能 陈永红1，杨洋1,2，杨雪1，田冬1，卢肖永1，丁岩芝1，林彬1,2 (1. 低温共烧材料安徽省重点实验室，淮南燃料电池材料工程技术研究中心，淮南师范学院，安徽淮南 232001； 2. 电子科技大学能源科学与工程学院，成都 611731) 摘要：采用柠檬酸-硝酸盐燃烧法制备PrBaFe2O5+δ(PBFO)和PrBaFe1.6Ni0.4O5+δ(PBFNO)电极材料，用高温固相法制备La0.9Sr0.1Ga0.8Mg0.2O3–δ(LSGM)电解质。以LSGM为电解质，PBFNO及PBFNO-SDC分别为对称电极制备单电池。利用X射线衍射法研究材料的物相结构，交流阻抗法记录界面极化行为，扫描电子显微镜观察电池的断面微结构，用自组装的测试系统评价电池输出性能。结果表明：合成的PBFO和PBFNO粉体呈现单一的钙钛矿结构；Ni掺杂能够明显改善空气气氛下的界面极化行为，800℃时电极–电解质的界面极化阻抗由1.94 ?·cm2降低到0.39?·cm2。通过PBFNO与SDC复合能够明显增大电极的三相反应界面，提高电池输出性能，单电池在800℃时的最大功率输出密度从332mW/cm2增大到372mW/cm2。PBFNO-SDC复合电极是潜在的对称固体氧化物燃料电池电极材料。 关键词：对称固体氧化物燃料电池；双钙钛矿；复合电极 中图分类号：TM911.47 文献标志码：A 文章编号：0454–5648(2017)11–1673–06 网络出版时间：2017–10–09 13:56:00 网络出版地址：https://www.doczj.com/doc/4115408526.html,/kcms/detail/11.2310.TQ.20171009.1356.008.html Preparation and Properties of Novel Symmetrical Solid Oxide Fuel Cells with Double Perovskite Electrodes CHEN Yonghong1, YANG Yang1,2, YANG Xue1, TIAN Dong1, LU Xiaoyong1, DING Yanzhi1, LIN Bin1,2 (1. Anhui Province Key Laboratory of Low Temperature Co-fired materials, Huainan Engineering Research Center for Fuel Cells, Huainan Normal University, Huainan 232001, China; 2. School of Energy Science and Engineering, University of Electronic Science and Technology of China, Chengdu 611731, China) Abstract: PrBaFe2O5+δ (PBFO) and PrBaFe1.6Ni0.4O5+δ(PBFNO) electrode materials were synthesized by a citric acid-nitrates self-propagating combustion method, and La0.9Sr0.1Ga0.8Mg0.2O3–δ (LSGM) electrolyte was prepared by a conventional solid-state reaction method. The LSGM-supported symmetrical solid oxide fuel cells using PBFNO and PBFNO-SDC as electrodes were prepared. The phase structure, polarization resistance, cross-section microstructure and the cell performance were investigated by X-ray diffraction, electrochemical impedance spectroscopy, scanning electron microscopy and self-assembly SOFC test system, respectively. The results indicate that PBFO and PBFNO powders calcined at 1 000 for 3 h both exhibit a single perovskite ℃ structure with cubic symmetry. The polarization performance is enhanced dramatically by Ni doping in air, which decreases from 1.94 ?·cm2 to 0.39 ?·cm2 at 800 . The maximum power density of cells increases from 3 ℃32 mW/cm2 to 372 mW/cm2 due to the enlarged triple-phase boundary by the introduction of SDC, indicating that PBFNO-SDC is a promising electrode material for symmetrical solid oxide fuel cells. Keywords: symmetrical solid oxide fuel cells; double perovskite; composite electrode 固体氧化物燃料电池(SOFCs)是一种能够将燃料的化学能直接转化为电能的电化学装置。由于其具有转换效率高、污染低、燃料适应性强等特点从而引起了人们的广泛关注[1–3]。传统的SOFCs是一 收稿日期：2017–06–30。修订日期：2017–08–12。 基金项目：国家自然科学基金(51102107)，安徽高校自然科学研究(KJ2017A459)资助项目。 第一作者：陈永红(1962—)，男，教授。 通信作者：林彬(1984—)，男，博士，教授。Received date: 2017–06–30. Revised date: 2017–08–12. First author: CHEN Yonghong (1962–), male, Professor. E-mail: chenyh@https://www.doczj.com/doc/4115408526.html, Correspondent author: LIN Bin (1984–), male, Ph.D., Professor. E-mail:bin@https://www.doczj.com/doc/4115408526.html,
石膏板吊顶工艺 一、施工准备 （一）作业条件 1.在所要吊顶的范围内，机电安装均已施工完毕，各种管线均已试压合格，已经隐蔽验收。 2.已确定灯位、通风口及各种照明孔口的位置。 3.顶棚罩面板安装前，应作完墙、地湿作业工程项目。 4.搭好顶棚施工操作平台架子。 5.轻钢骨架顶棚在大面积施工前，应做样板，对顶棚的起拱度、灯槽、窗帘盒、通风口等处进行构造处理，经鉴定后再大面积施工。 （二）材料准备 轻钢龙骨、配件、吊杆、膨胀螺栓、自攻螺钉、拉铆钉、石膏板、纸带、石膏粉等，进场检验合格且有出厂质量证明文件。 （三）施工机具 型材切割机、电动曲线锯、手电钻、电锤、自攻螺钉钻、手提电动砂纸机等。 二、质量要求 （一）暗龙骨吊顶工程 质量要求符合《建筑装饰装修工程施工质量验收规范》（GB50209－2002）的规定。 （二）明龙骨吊顶工程 质量要求符合《建筑装饰装修工程施工质量验收规范》（GB50209－2002）的规定。 三、工艺流程 弹顶棚标高水平线--画龙骨分档线--安装主龙骨吊杆--安装主龙骨--安装边龙骨--安装次龙骨--安装石膏板--涂料--饰面清理--分项--检验批验收
四、施工工艺 1.弹顶棚水平线：根据设计标高，沿墙四周弹顶棚标高水平线，并沿顶棚的标高水平线，在墙上画好龙骨分档位置线。 2.安装主龙骨吊杆：在弹好顶棚标高水平线及龙位置线后，确定吊杆下端头的标高，安装∮8吊杆。直安装选用膨胀螺栓固定到结构顶棚上。吊杆选用规格符合设计要求，间距小于1200mm。 3.安装主龙骨：主龙间距为900~1200mm。主龙骨用与之配套的龙吊件与吊杆相连。 4.安装次龙骨：次龙骨间距为500mm～600mm，采用次挂件与主龙骨连接。 5.刷防锈漆：轻钢骨架罩面板顶棚吊杆、固定吊杆铁件，在封罩面板前应刷防锈漆。 6.安装石膏板：石膏板与轻钢骨架固定的方式采用自攻螺钉固定法，在已装好并经验收轻钢骨架下面（即做隐蔽验收工作），安装9.5mm厚反。安装石膏板用自攻螺丝固定，固定间距板边为200mm，板中为300mm。自攻螺丝固定后点刷防锈漆。 7.接缝处理：在板缝间采用粘贴纸带嵌缝膏进行嵌缝处理。 8.吊顶验收时应检查下列文件和记录： ①吊顶工程的施工图、设计说明及其他设计文件； ②材料的产品合格证书、性能检测报告、进场验收记录和复验报告； ③隐蔽工程验收记录； ④施工记录。 五、成品保护 1.轻钢骨架、罩面板及其他吊顶材料在入场存放、使用过程中应严格管理，保证不变形、不受潮，不生锈。 2.装修吊顶用吊杆严禁挪做机电管道、线路程吊挂用；机电管道、线路如与吊顶吊杆位置矛盾，须经过项目技术人员同意后更改、不得随意改变、挪动吊杆。 3.吊顶龙上禁止铺设机电管道、线路。
四硅钙板吊顶施工方案 1、材料及配件要求 1.1硅钙板的规格、品种、表面形式必须达到设计要求和使用功能的要求。 1.2吊顶使用的轻钢龙骨分为U形骨架和T形骨架两种，并按照荷载不同分为上人和不上人两种。 1.3轻钢龙骨分为主龙骨、次龙骨、边龙骨；配件有吊件、连接件、挂插件等材质必须符合设计要求。 1.4零配件：吊杆、花篮螺丝、射钉、自攻螺丝等。 1.5按照设计或样品要求可选用各种罩面板 2、主要施工机具 电锯、射钉枪、手锯、钳子、螺丝刀、方尺、钢尺、钢水平尺等。 3、施工作业的相关条件 3.1材料准备：在施工前必须提前准备好吊顶所用的吊杆，一般吊杆选用Φ6～Φ10的钢筋，并且一端需要进行套丝（长度不小于50mm），如果顶棚有预埋件可以将吊杆直接与之焊接，没有预埋件则需要用30*3的角钢切成40mm左右一段，一边打孔，一边与吊杆焊接（焊接长度不小于20mm，双面焊）。设计无要求时预埋件间距为900-1200mm。 在房间的四周墙、柱上，按照吊顶标高位置打孔预埋好防腐木楔，间距600mm左右（按照矿棉板的规格设置）。 3.2顶棚内的各种设备安装工程必须施工完毕，通风管道的标高与吊顶标高无矛盾，检查口、风洞口以及各种明露孔位置确定。 3.3吊顶所需的龙骨、配件、面板提前准备齐全。 3.4安装矿棉板或安装边龙骨前墙面的必须刮两遍腻子找平，否则造成墙面与顶棚阴角处不易处理好。
4、施工工艺 4.1工艺流程： 4.2.施工技术措施： （1）弹线：根据事先从标高点引出的标高弹出50cm 控制线，并依据弹出的控制线确定各房间吊顶设计标高的标准线。在墙上划出龙骨的分档控制点，一般距离900-1200mm 左右。 （2）安装吊筋：根据施工大样图纸要求确定吊筋的位置，安装吊筋前，刷防锈漆。吊杆采用直径为Φ6的钢筋制作并刷防锈漆，吊点间距900-1200mm 。安装时上端与铁胀栓连接，下端套丝后与吊件连接。安装完毕的吊杆端头外露长度不小于3MM 。 （3）安装主龙骨：采用UC50或U38龙骨，吊顶主龙骨间距为小于1200MM 。安装主龙骨时，应将主龙骨吊挂件连接在主龙骨上，拧紧螺丝，并根据设计要求吊顶起拱 ，起拱高度约为短跨的1/200，并且安装的主龙骨接长应错开，在接头处增加吊点，随时检查龙骨的平整度。当遇到通风管道较大超过龙骨最大间距要求时，必须采用30*3以上的角钢做龙骨骨架，并且不能将骨架与通风管道等设备工程接触。 （4）安装次龙骨：按照面板的不同安装方式和规格，次龙骨分为T 形和C 形两种，次龙骨间距为600mm ，将次龙骨通过挂件吊挂在大龙骨上，在与主龙骨平行方向安装600MM 的横撑龙骨，间距为600MM 或1200MM 。当采用搁置法和企口法安装时次龙骨为T 形，粘贴法或者其他固定法时选用C 形。 （5）安装边龙骨：采用L 型边龙骨，与墙体用塑料胀管或自攻螺钉固定，固定
一、钙钛矿结构示意图 钙钛矿型复合氧化物是结构与钙钛矿CaTiO3相同的一大类化合物，钙钛矿结构可以用ABO3表示（见上图），A位为稀土元素，阳离子呈12配位结构，位于由八面体构成的空穴内；B位为过渡金属元素，阳离子与六个氧离子形成八面体配位。钙钛矿型催化剂在中高温活性高，热稳定性好，成本低。研究发现，表面吸附氧和晶格氧同时影响钙钛矿催化活性。较低温度时，表面吸附氧起主要的氧化作用，这类吸附氧能力由B位置金属决定；温度较高时，晶格氧起作用，不仅改变A、B 位置的金属元素可以调节晶格氧数量和活性，用+2或+4价的原子部分替代晶格中+3价的A、B原子也能产生晶格缺陷或晶格氧，进而提高催化活性。 二、双钙钛矿结构示意图 近年来，双钙钛矿型氧化物得到了越来越广泛的关注，双钙钛矿的通式可表示为A2B’B’’O6，标准的A2B’B’’O6型氧化物可以看作是由不同的BO6八面体规则的相间排列而成。一般情况下B′和B″是不同的过渡金属离子，其晶体结构如图2所示。A2B’B’’O6结构双层钙钛矿型复合氧化物呈NaCl型结构相见排列。多数情况下双层钙钛矿氧化物结构也将发生畸变，它的结构一般由离子
大小、电子组态和离子间相互作用等决定，而且双钙钛矿结构中B’O6和B’’O6八面体的稳定性对整个结构的稳定性起着很重要的作用，B′位、B″位离子相应的氧化物越稳定，则钙钛矿结构越稳定。双钙钛矿型复合氧化物的制备近年已成为材料科学的重要发展方向。从理论角度上看，双钙钛矿氧化物材料可以提供更加丰富的变换组合，给研究者提供了广阔的研究空间。 Sr2FeMoO6属于典型的A2B’B’’O6结构氧化物，其理想形式为Fe3+和Mo5+分别有序地占据B′和B″位置，FeO6八面体和MoO6八面体在三维空间以共角顶的方式相间排列组成三维框架，Sr2+则填充在由8个八面体所围成的空隙的中心位置，如上图所示。实际上，由于占据A位、B′位及B″位的Sr2+、Fe3+、Mo5+并不是像标准立方双钙钛矿结构那样完全匹配，因此，在常温下其结构并非为立方对称，而是沿c轴方向有一个拉伸，畸变为四方对称结构。大量的研究表明，Sr2FeMoO6中存在Fe/Mo离子的反位缺陷(反位缺陷是指Fe离子占据Mo位而Mo离子占据Fe位)，而且反位缺陷对Sr2FeMoO6的电输运性质和磁学性质有很大的影响。
三、石膏板吊顶施工工艺 令狐采学 1、施工准备 1）原材料、半成品要求 木料：木龙骨料应为烘干，无扭曲的红、白松树种，并按设计要求进行防火处理。木龙骨规格按设计要求，如设计无明确规定时，大龙骨规格为50mm×70m m或50mm×100m m；小龙骨规格为50mm×50m m或40mm×50m m；木吊杆规格为50mm×50m m或40mm×40m m。罩面板材及压条。 纸面石膏板选用时严格掌握材质及规格标准。 其它材料 φ6或φ8吊筋、膨胀螺栓、射钉、圆钉、角钢、扁钢、胶粘剂、木材防腐剂、防火剂、8号镀锌铁丝、防锈漆。 2）作业条件 现浇楼板中按设计间距埋设φ6或φ8吊筋。当设计未做说明时，间距一般不大于1000mm。 墙为砌体时，应根据顶棚标高，在四周墙上预埋固定龙骨的木砖。 直接接触墙体的木龙骨，应预先刷防腐剂。 按工程不同防火等级和所处环境要求，对木龙骨进行喷涂防火涂料或置于防火涂料槽内浸渍处理。
顶棚内各种管线及通风管道均已安装完毕并经验收合格。各种灯具、报警器预留位置已经明确。 墙面及楼、地面湿作业和屋面防水已做完。 室内环境力求干燥，满足木龙骨吊顶作业的环境要求。 2、施工工艺 1）抄平弹线 弹线包括：标高线、顶棚造型位置线、吊挂点布局线、大中型灯位线。 确定标高线：根据室内墙上+50cm水平线，用尺量至顶棚设计标高，在该点画出高度线，用一条塑料透明软管灌满水后，将软管的一端水平面对准墙面上的高度线。再将软管的另一端头水平面，在同侧墙面找出另一点，当软管内水平面静止时，画下该点的水平面位置，再将这两点连线，即得吊顶高度水平线。用同样方法在其它墙面做出高度水平线。操作时应注意，一个房间的基准高度点只用一个，各个墙的高度线测点共用。沿墙四周弹一道墨线，这条线便是吊顶四周的水平线，其偏差不能大于5mm。 确定造型位置线：对于较规则的建筑空间，其吊顶造型位置可先在一个墙面量出竖向距离，以此画出其它墙面的水平线，即得吊顶位置外框线，而后逐步找出各局部的造型框架线。对于不规则的空间画吊顶造型线，宜采用找点法，即根据施工图纸测出造型边缘距墙面的距离，从墙面和顶棚基层进行实测，找出吊顶
硅酸钙板施工工艺及流 程 集团公司文件内部编码：（TTT-UUTT-MMYB-URTTY-ITTLTY-
硅酸钙板施工 1、作业条件 1）吊顶工程在施工前应热悉施工图纸及设计说明。 2）吊顶工程在施工前应熟悉现场。 3）施工前应按设计要求对房间的净高、洞口标高和吊顶内的管道、设备及其支架的标高进行交接检验。 4）对吊顶内的管道、设备的安装及水管试压进行验收。 5）吊顶工程在施工中应做好各项施工记录，收集好各种有关文件。 6）材料进场验收记录和复验报告，技术交底记录。 7）板安装时室内湿度不宜大于70％以上。 2、施工工艺流程 吊顶标高弹水平线一划龙骨分档线一安装水电管线一安装主龙骨一安装次龙骨一安装罩面板一安装压条 3、操作工艺 1）弹线 用水准仪在房间内每个墙(柱)角上抄出水平点(若墙体较长，中间也应适当抄几个点)，弹出水准线(水准线距地面一般为500mm)，从水准线量至吊顶设计高度加上12mm(一层硅酸盖板的厚度)，用粉线沿墙(柱)弹出水准线，即为吊顶次龙骨的下皮线。同时，按吊顶平面图，在混凝土顶板弹出主龙骨的位置。主龙骨应从吊顶中心向两边分，最大间距
为1000mm，并标出吊杆的固定点，吊杆的固定点间900～1000mm。如遇到梁和管道固定点大于设计和规程要求，应增加吊杆的固定点。 2）固定吊挂杆件 现浇钢筋混凝土板底预留直径8mm钢筋吊环双向中距小于1200；直径6mm钢筋吊环，双向中距小于1200吊杆上部与板底预留吊环固定；U型轻钢主龙骨CB38*12，中距小于1200找平后与钢筋吊杆固定；H型轻钢次龙骨LB20*20，中距600。制作好的吊杆应做防锈处理，吊杆用膨胀螺栓固定在楼板上，用冲击电锤打孔，孔径应稍大于膨胀螺栓的直径。 3）在梁上设置吊挂杆件 吊挂杆件应通直并有足够的承载能力。长时，必须搭接焊牢，焊缝要均匀饱满；吊杆距主龙骨端部距离不得超过300mm，否则应增加吊杆；吊顶灯具、风口及检修口等应设附加吊杆。 4）安装边龙骨 边龙骨的安装应按设计要求弹线，沿墙(柱)上的水平龙骨线把L形镀锌轻钢条用自攻螺丝固定在预埋木砖上；如为混凝土墙(柱)，可用射钉固定，射钉间距应不大于吊顶次龙骨的间距。 5）安装主龙骨 主龙骨应吊挂在吊杆上。主龙骨间距900一1000mm。主龙骨分为轻钢龙骨和T形龙骨。轻钢龙骨选用UC50中龙骨和UC38小龙骨。主龙骨应平行房间长向安装，同时应起拱，起拱高度为房间跨度的1／200～1／300。主龙骨的悬臂段不应大于300ram，否则应增加吊杆。主龙骨的接长应采取对接，相邻龙骨的对接接头要相互错开。主龙骨挂好后应
本帖最后由asc3793 于2016-6-10 21:40 编辑 1；石膏板吊顶施工标准做法 一、工艺流程 1、适用范围 适用于电梯前室、首层大堂顶棚装修施工 2、工艺流程 弹线→水电隐蔽工程安装→安装吊筋→安装主龙骨→安装次龙骨→隐蔽工程检验→安装面层石膏板→腻子及表面涂料施工→安装灯具电器→清洁。 二、控制标准及注意事项 1、公装施工前，必须做公装施工样板，对吊顶内管线等进行优化，明确各部件的位置关系及施工工艺，公装样板经技术部确认后，方可进行大面积施工。 2、公装过程需报质监站验收，施工单位应提前咨询主管部门，否则有可能影响单位工程质监验收。 3、总包单位与公装单位顶棚部位交接面为素混凝土交接。 4、进场材料的品牌与甲方指定品牌相符，且需提供材料合格证、质保书、3C认证等书面资料；并按以下要求对材料进行检查： 1）胶合板：主要检测甲醛释放量和胶合强度，以及标称厚度与实际厚度是否相符； 2）铝扣板：主要检测外观质量、厚度（批量装修时，采购的厚度宜≥0.7mm）、静载加载挠度以及相应的表面处理质量等。龙骨及配件的质量检查，要注意尺寸要求，外观要求，镀锌量以及弹塑性变形量，挠度等。 3）纸面石膏板：应平整，对于波纹、沟槽、污痕和划伤等缺陷，按规定方法检测时，应符合规定。检测外观质量时应在0.5m远处光照明亮的条件下，进行目测检查。
5、石膏板吊顶，宜采用不锈钢螺丝钉，且所有螺丝必须做防锈处理；螺丝头宜略埋入板面，约0.5mm； 4、主龙骨的相互间距≤1.2m，固定板材的次龙骨间距≤600mm；吊杆长度≥1.5m时，应设置反支撑，禁止采用铁丝代替吊杆；当吊杆与设备相遇时，应调整吊点构造或增设吊杆。主龙骨应根据设计要求起拱，如设计中无明确要求时，应按吊顶区域短向跨度的1/200～1/300起拱。主龙骨安装后应及时校正其位置和标高。 5、顶棚采用的材料必须达到耐火等级要求，采用木质构件等可燃物必须经过防火处理。 6、天花封板前，必须检查天花电管线安装，包括电气及消防管线等，电线穿线完成，管道通水打压完成，防止天棚安装完成后，再进行调整。 7、天花板安装时，应调整灯位、烟感探头、消防喷嘴等外露部位，灯位、烟感等应按图纸对称或居中分布，消防喷嘴外露长度应合适且每个喷嘴的外露长度应相同。 8、大堂内较重的灯具等，必须连接到混凝土顶板上，不得直接挂到吊顶龙骨上。顶棚内的管线必须单独设置吊杆，不得借用龙骨吊杆。 9、纸面石膏板吊顶工程，如设计无明确要求时，应在边角隐蔽处或吊顶内重要设备部位，设置检查孔，以便于设备检修。 10、吊顶安装后如需上人维修吊顶内部设备，应踩踏龙骨，不得直接踩踏石膏板、木夹板等吊顶板面部位，以免造成板面断裂。 三、记录控制 1、施工样板验收记录 2、材料进场检查记录 3、天棚管线等隐检记录。 2；块料铺装施工标准做法 一、工艺流程： 1、适用范围 适用于电梯厅、大堂墙面块料铺装施工。 2、工艺流程 基层处理→弹线→贴面砖或石材→勾缝→表面清洁（及打磨）→成品保护。