Combining endogenous SND and P removal with post denitrification for low CN wastewater treatment
Combining simultaneous nitri?cation-endogenous denitri?cation and phosphorus removal with post-denitri?cation for low carbon/nitrogen wastewater
treatment
Xiaoxia Wang,further reduce 64%TN in ef?uent.
Average ef?uent PO 43à
-P and TN
concentrations were 0.4and 3.9mg/L,respectively.
a r t i c l e i n f o Article history:
Received 5May 2016
Received in revised form 28June 2016Accepted 30June 2016
Available online 2July 2016
Keywords:
Simultaneous nitri?cation-endogenous denitri?cation and phosphorus removal (SNDPR)
Post-denitri?cation (PD)Partial nitri?cation (PN)
Phosphorus accumulating organisms (PAOs)Glycogen accumulating organisms (GAOs)
a b s t r a c t
Due to the limited nutrient removal from low carbon/nitrogen (64)wastewater,a process combined simultaneous nitri?cation-endogenous denitri?cation and phosphorus removal (SNDPR)with post-denitri?cation (PD)in a SBR was proposed for deep-level nutrient removal without external carbon addi-tion.SNDPR driven by PAOs and GAOs reduced PO 43à
-P (98.3%)and partial TN (59.0%)at low DO condi-tions (0.5±0.1mg/L),and post-dentri?cation achieved further NO X à(produced by SNDPR)removal (24.0%)anoxically by utilizing the residual intracellular polymers in https://www.sodocs.net/doc/5117823863.html,bined control of anaero-bic/aerobic/anoxic durations and low DO inhibition to aerobic GAOs and NOB conducted partial nitri?cation-endogenous denitri?cation (PNED)(66%),which saved 44.3%intracellular polymers to fur-ther reduce 64%TN in ef?uent.After 115-day operation,the average ef?uent PO 43à
-P and TN concentra-tions were 0.4and 3.9mg/L,respectively,with 92.1%of TN removal.Highly enriched PAOs (36%±2%),GAOs (22%±2%)and AOB (15%±3%)over NOB (3%±1%)facilitated P uptake,PNED
and post-denitri?cation in the SNDPR-PD system.
ó2016Published by Elsevier Ltd.
1.Introduction
In wastewater treatment plants (WWTPs),phosphorus (P)removal always accompanies with nitrogen (N)removal,both
requiring organic carbon which is often limiting
(Zhang et al.,2013).Simultaneous nitri?cation-endogenous denitri?cation and phosphorus removal (SNDPR)was reported to ef?ciently utilize the carbon source in raw wastewater by strengthening the anaer-obic intracellular carbon storage (Wang et al.,2015).At the anaer-obic stage,phosphorus-and-glycogen accumulating organisms (PAOs and GAOs)take up carbon sources in in?uent,primarily volatile fatty acids (VFAs),and store them in the form of poly-
https://www.sodocs.net/doc/5117823863.html,/10.1016/j.biortech.2016.06.1320960-8524/ó2016Published by Elsevier Ltd.
?Corresponding author.
E-mail address:wsy@https://www.sodocs.net/doc/5117823863.html, (S.Wang).
hydroxyalkanoates(PHAs),with the energy gained from the degra-dation of glycogen(Gly)with/without the degradation of polyphosphate(Oehmen et al.,2007;Pijuan et al.,2010).At aerobic stage,PAOs and GAOs regenerate Gly with/without P uptake using the stored PHAs,and ammonia and nitrite oxidizing bacteria(AOB and NOB)conduct nitri?cation.More importantly,both denitrify-ing PAOs-and-GAOs(DPAOs and DGAOs)conduct N removal at the aerobic stage(Zeng et al.,2003a;Meyer et al.,2005;Wang et al.,2015).Thus,simultaneous N and P removal is achieved in SNDPR systems.
However,at the aerobic stage of SNDPR system,PAOs,GAOs, AOB and NOB compete for dissolved oxygen(DO),which always result in incomplete ammonia oxidation and excess intracellular carbons waste without contributing to endougenous dentri?cation (Wang et al.,2015).Both nitrite and nitrate were the nitri?cation products by AOB,which would lately become the electron accep-tors for DGAOs,DPAOs and https://www.sodocs.net/doc/5117823863.html,pared with nitrite pathway, endogenous denitri?cation via nitrate consumes50%more PHAs (Wang et al.,2016).Suitable DO concentration and aerobic dura-tion are particularly the case for SNDPR optimization and nutrient removal via nitrite.Previous reports on SNDPR optimizations were just accomplished by adding aerobic granular(Bassin et al.,2012; Coma et al.,2012)or bio?lms(Wang et al.,2009a;Yang et al., 2010)or extending anaerobic durations to enhance SND(de Kreuk et al.,2005;Wang et al.,2015),and the PO43à-P and TN removal ef?ciencies were still low(52%and71%in Wang et al. (2009);82%and84%in Yang et al.(2010);80%and30%in Bassin et al.(2012);75%and93%in Coma et al.(2012);78%and94%in Wang et al.(2015)).Therefore,highly ef?cient sewage treatment process based on SNDPR and control strategies should be devel-oped for advanced nutrient removal.
Post-denitri?cation(PD)process driven by GAOs could achieve N removal anoxically using both PHAs and Gly(Qin et al.,2005; Coats et al.,2011).Considering that SNDPRs always contains high amounts of PHAs and Gly due to the highly enriched GAOs and PAOs(Wang et al.,2015;Coma et al.,2012),it is extremely signif-icant to achieve advanced N and P removal via full utilization of intracellular polymers stored in PAOs and GAOs by combining SNDPR with post-dentri?cation(termed as SNDPR-PD).On the one hand,the SNDPR could reduce PO43à-P and partial TN at low aeration intensity;on the other hand,the post-dentri?cation could further remove the NO Xà(NO2à-N and NO3à-N)produced by SNDPR, and thus reducing the carbon demand for denitrifying OHOs and leading to more carbon sources available for SNDPR-PD.For now, post-denitri?cation driven by PHAs and Gly has been reported for nitrogen removal from land?ll leachate treatment(Li et al., 2014;Miao et al.,2015).Land?ll leachate contains high amounts of organic substances and low amounts of phosphorus,making it suitable to enrich GAOs to conduct endogenous dentri?cation (Miao et al.,2015).Post-denitri?cation process with/without SNDPR for the treatment of real domestic wastewater with low carbon/nitrogen ratio(C/N,referred to chemical oxygen demand (COD)/total nitrogen(TN))(64)without external carbon addition has not been reported.
This study aims at developing a SNDPR combined with post-denitri?cation process in a single sequencing batch reactor(SBR) and exploring the feasibility of the system for deep-level C,N and P removal from low C/N ratio(64)wastewater without exter-nal carbon addition.By comprehensively regulating the anaerobic, aerobic and anoxic durations and DO concentration,the SNDPR was?rstly optimized and lately combined with post-dentri?caition,during which the P uptake,PHAs degradation,Gly production,SND ef?ciency and ef?uent TN concentrations were monitored and stoichiometry-based analyzed to evaluate the enhanced nutrient removal performance.The enhanced nutrient removal was also veri?ed by the population dynamics and activity variations of functional microorganisms.Finally,performance of the SNDPR-PD system was compared with other related systems to demonstrate its superiority.
2.Materials and methods
2.1.SBR operation for the SNDPR-PD system
A laboratory-scale open-mouthed SBR with a working volume of8L and fed with domestic wastewater was used in this study (Fig.1).The SBR was operated at room temperature,and operated under extended anaerobic,short aerobic conditions with low DO concentration and anoxic conditions.During all anaerobic,aerobic and anoxic periods,an agitator was used to keep the sludge in sus-pension.During the aeration period,DO concentration was stably maintained using an online real-time control device(PLC).In each cycle,3L domestic wastewater was added into the reactor in the beginning of the anaerobic stage;200mL of mixed liquor was removed in the end of the aerobic stage to achieve a mixed liquor volatile suspended solid(MLVSS)level of2200±500mg/L.More detailed operation conditions of the SBR were shown in Table1.
2.2.Domestic wastewater and seeding sludge
Domestic wastewater was taken from a septic tank in the resi-dential area of Beijing University of Technology(Beijing,China). The wastewater has a low C/N ratio(average 3.5)with COD 203.8–281.6mg/L,VFAs123.2–182.8mg/L(acetic acid118.1–174.4mg/L,propionic acid 1.8–6.2mg/L,n-butyric<5mg/L, iso-butyric acid<5mg/L,iso-valeric<3.5mg/L),BOD5 114.8–177.3mg/L,NH4+-N48.4–69.0mg/L,NO2—N<1mg/L,NO3—N <1mg/L,PO43à-P 5.1–7.9mg/L,and TN61.4–79.5mg/L.The activated sludge inoculated was taken from an ongoing lab-scale SBR system(working volume:8L)which had achieved a stable performance of biological N and P removal for6months(Wang et al.,2015).
2.3.Methods for chemical analysis
Mixed liquor samples were?ltered through0.45l m?lter paper before analysis.NH4+-N,NO2à-N,NO3à-N,and PO43à-P were analyzed using Lachat Quik-Chem8500Flow Injection Analyzer(Lachat Instrument,Milwau-kee,USA).BOD5,COD,MLSS,MLVSS,sludge volume index(SVI)and SV%were analyzed according to standard methods(APHA,1998).VFAs were analyzed using a gas chro-matograph(GC,Agilent7890).TN was analyzed using a TN analyzer (Multi N/C3000,Ananlitijena AG,Germany).PHAs were deter-mined by the sum of PHB and PHV,both PHB and PHV were ana-lyzed according to Oehmen et al.(2005).Glycogen was analyzed according to Zeng et al.(2003b).Scanning electron microscopy (SEM)was conducted to elucidate the microscopic behavior of acti-vated sludge.
2.4.Methods for microbial community identi?cation
Fluorescence in situ hybridization(FISH)was used to quantify AOB,NOB,PAOs and GAOs(Amann et al.,1990),and quanti?cation of DPAOs in PAOs was calculated by Wachtmeister et al.(1997). FISH probes used were:EUB mix(comprising equal amounts of EUB338,EUB338-II,and EUB338-III)for most Eubacteria;PAO mix (comprising equal amounts of PAO462,PAO651,and PAO846)for Accumulibacter;GAO mix(comprising equal amounts of GAO431 and GAO989)for Competibacter(Wang et al.,2015);NSO190for b-proteobacterial AOB speci?c,NSO1225for Nitrosomonas spp.,
18X.Wang et al./Bioresource Technology220(2016)17–25
Ntspa662for Nitrospira genera,and NIT3for Nitrobacter sp.(Wang et al.,2016).
2.5.Calculation of COD intra ef?ciency
Intracellular carbon storage (COD intra )ef?ciency at the anaero-bic stage of the SNDPR-PD system is de?ned as the proportion of external COD which was not consumed by denitrifying OHOs for exogenous denitri?cation (Eq.(1)).COD intra plays an important part in the ef?cient N and P removal at the subsequent aerobic and anoxic stages by providing suf?cient intracellular carbons for endogenous denitri?cation and P uptake (Oehmen et al.,2007;Wang et al.,2015).
COD int ra e%T?1à
1:71NO à2;i àNO à2;ana t2:86NO à3;i àNO à
3;ana
i àCOD ana
0@1
A ?100%
e1T
where,2.86and 1.71are the theoretical value of COD consump-tion for denitri?cation of per unit NO 3à-N and NO 2à
-N,respectively,
mgN/mgCOD;COD i ,NO à3;i and NO 2à
,i
are the concentrations of COD,NO 3à-N and NO 2à
-N at the beginning of anaerobic stage,while COD ana ,
NO à3;ana and NO à
2;ana are their concentrations at the end of anaerobic stage,mg/L.
3.Results and discussion
3.1.C,N and P removal performance of the SNDPR-PD system The SBR was optimized for 115days to further improve the N and P removal based on the operation strategy described in Table 1.The whole operation period was divided into 4phases based on the nutrient removal performance (Fig.2).
In phase 1(1–11d),the average ef?uent COD,TN and PO 43à
-P concentrations were 43.5,13.2and 0.3mg/L,respectively,with anaerobic P release amount (PRA)of 26.7mg/L (Fig.2A and B).NH 4+-N and TN removal ef?ciencies were 96.6%and 77.2%,respec-tively,with an average COD intra ef?ciency of 80.1%(Fig.2B and C).The high COD intra led to ef?cient N and P removal in the SBR by facilitating endogenous denitri?cation and phosphorus removal (SND ef?ciency was 47.7%,calculated by Lo et al.(2010)).
In phase 2(12–50d),the aerobic DO concentration was decreased to 0.5±0.1mg/L to enhance SND and improve N removal (Table 1).Hereafter,SND ef?ciency was improved,with ef?uent NO 3à-N concentration decreasing to 3.8mg/L on the 31th day and COD intra ef?ciency increasing to 90.5%(Fig.2C).Results indicated that low DO concentration was bene?cial for SND by pro-viding DO gradient within the microenvironment of ?occulent sludge for denitri?cation bacteria (Meyer et al.,2005).However,
ef?uent NH 4+-N and NO 2à
-N concentrations gradually increased to 5.0and 1.8mg/L,respectively,followed by TN removal ef?ciency gradually decreasing to 72.7%(Fig.2B),indicating that nitri?cation
PLC
Feed tank
Influent pump
Effluent tank
Computer
Air pump
Sampling valve
Agitator
pH/DO meter
pH/DO probe Aerator
Waste sludge tank
Gas flow meter
80
3
7.8/0.5
Feed (10 min)
Anaerobic stage (150 min)Aerobic stage with low DO
(180 min)
Anoxic stage (120 min)
Settle (20 min)Decant idle
480 min
Intracelluar carbon
storage SNDPR Post-denitrification device (A)and operation process (B)of the SNDPR combined with post-denitri?cation Table 1
Operation conditions for the SNDPR-PD system over 115-day operational period.Items Phase 1(1–11d)Phase 2(12–50d)Phase 3(51–75d)Phase 4(76–115d)Operation mode Anaerobic/aerobic Anaerobic/aerobic Anaerobic/aerobic Anaerobic/aerobic/Anoxic Anaerobic time (min)180180150150Aerobic time (min)150150180180
Anoxic time (min)000120HRT (h)14.614.614.620SRT (d)
10.910.910.912.0Anaerobic DO (mg/L)<0.04<0.04<0.04<0.04Aerobic DO (mg/L)
1.0±0.3
0.5±0.1
0.5±0.1
0.5±0.1
X.Wang et al./Bioresource Technology 220(2016)17–2519
was affected by insuf?cient DO.Ef?uent PO43à-P concentration maintained below0.5mg/L,followed by a stable P release and uptake performance as in phase1(Fig.2A),indicating that DO had no obvious effect on PAOs activity.
Based on the incomplete nitri?cation in phase2,aerobic dura-tion was increased to180min in phase3(51–75d)with anaerobic duration decreased to150min(Table1).Ef?uent NH4+-N decreased to 1.1mg/L on the75th day,followed by ef?uent NO2à-N and NO3à-N concentrations slightly increasing to 4.4and 5.3mg/L, respectively.TN removal ef?ciency was strengthened to81.7%,fol-lowed by constant COD intra ef?ciency,SND ef?ciency and P removal.The results indicated that extending aerobic time ensured complete ammonia oxidation,and anaerobic intracellular carbon storage was not affected by reducing anaerobic time(COD at the end of anaerobic stage was nearly equal to ef?uent COD,Fig.2A).
In phase4(76–115d),an anoxic stage was added at the end of aerobic stage(Table1)to further improve the system N removal performance.Ef?uent PO43à-P concentration was stably below 0.5mg/L with a slight decrease in PRA.Ef?uent NH4+-N concentra-tion and SND ef?ciency were similar as in phase3(about1.2mg/L and57.6%,respectively),but ef?uent NO2à-N and NO3à-N concentra-tions were further reduced to2.4and0.4mg/L,respectively,?o-wed by TN removal ef?ciency further improved to92.1% (Fig.2B and C).Additionally,COD intra ef?ciency was further enhanced to96.2%due to the decrease of ef?uent NO2à-N and NO3à-N concentrations.The results proved the feasibility of comb-ing SNDPR with post-denitri?cation for further nutrient removal. The SNDPR-PD process has the unique advantage for treating wastewater with low C/N ratio(3.5)over traditional biological nutrient removal(BNR)processes(92.1%and93.9%of TN and PO43à-P removal in this study,while67%and89%in A2N-SBR(C/ N ratio3.5,Wang et al.,2009b),83%and99%in A2O-BAF(C/N ratio 4,Zhang et al.,2013),and about85%and95%in modi?ed UCT(C/N ratio8,Ge et al.,2013;Vaiopoulou et al.,2007)).
Additionally,SVI of the SNDPR-PD process in phase4main-tained at about136mL/g during the4operational phases (Fig.S1),similar to traditional BNR processes(120–150mL/g,Ge et al.,2013;Vaiopoulou et al.,2007;Vaiopoulou and Aivasidis, 2008).The average SV%and MLVSS were37and2255mg/L, respectively.The results indicated the good settleability of the SNDPR-PD system operated under low DO concentrations (0.5±0.1mg/L).SEM results illustrated that the microbial mor-phology of activated sludge was given priority to coccus,with very little bacillus and?lamentous bacteria(Fig.S1).The compact struc-ture of the activated sludge con?rmed the good settleability of the SNDPR-PD process.
3.2.Population dynamics of functional microorganisms linked with nutrient removal performance
FISH results illustrated that PAOs(including49.2%of DPAOs) and GAOs accounted for38%±2%and21%±3%of total biomass on day1in phase1(Fig.3A).The enriched PAOs and GAOs ensured the anaerobic intracellular carbons storage(COD intra ef?ciency was 81.1%,Table2)and the nutrient removal at aerobic stage.AOB accounted for18%±3%of total biomass with NOB accounted for
6%±2%,which ensured nitri?cation at the aerobic stage of the SBR(Fig.3B and C).
On day50in phase2,both PAOs and GAOs populations main-tained at the high level as in phase1,but the proportion of DPAOs in PAOs increased by7.3%(Fig.3A)due to the decrease of DO con-centration.AOB and NOB populations decreased by3%and2%, respectively,compared with phase1,indicated that the decrease of ef?uent NO3à-N concentration in phase2was partially caused by the reduction of both AOB(mainly b-proteobacterial AOB speci?c,Fig.S2)and NOB,while the increase of ef?uent NO2à-N concentration was caused by the reduction of NOB(mainly Nitrobacter sp.,Fig.S2).However,the slight increase of DPAOs (with/without DGAOs)population and decrease of NOB population increased SND ef?ciency by$13%comparing with phase1.
On day75in phase3,PAOs,GAOs and AOB maintained at high population percentages as in phase2,but DPAOs increased to 62.4%in total PAOs,with NOB decreased to3%±1%of total bio-mass(Fig.3).Compared with phase1,50%reduction of NOB (mainly Nitrospira genera,Fig.S2)population inosculated with
20X.Wang et al./Bioresource Technology220(2016)17–25
the increased ef?uent NO2à-N concentration and decreased ef?uent NO3à-N concentration(Fig.2B)in the SBR,proved the lower growth rate of NOB than AOB at low DO concentration(Tokutomi,2004). Compared with phase2,further enriched DPAOs(with/without DGAOs)improved SND ef?ciency and TN removal ef?ciency by 2%and7.9%,respectively(Table2).
On day112in phase4,both AOB and NOB populations stably maintained at15%±3%and3%±1%,respectively,with a low ef?u-ent NH4+-N concentration and a stable nitri?cation performance (Fig.3and Table2).PAOs decreased to36%±2%of total biomass with DPAOs reached66.7%of PAOs(Fig.3A).GAOs increased to 22%±2%of total biomass(Fig.3A).The decreased PAOs population consisted with the decreased anaerobic PRA,but the increased GAOs population improved the TN removal ef?ciency to92.1%by conducting endogenous denitri?cation at the anoxic stage of the SBR.Additionally,SND ef?ciency was not improved($60%,as in phase3,Table2)along with the further increased DPAOs popula-tion.The possible reason was the decreased DGAOs activity at the aerobic stage.Therefore,population variations of functional microorganisms elucidated the enhanced nutrient removal perfor-mance of the SNDPR-PD system from phase1to phase4.
3.3.Nutrient removal mechanism of the SNDPR-PD system
Variations of nitrogen,phosphorus,extracellular and intracellu-lar carbon sources in a typical cycle(8h)on day112(phase4,with enhanced N and P removal performance)were analyzed to investi-gate the nutrient removal mechanism of the SNDPR-PD system. The anaerobic initial NH4+-N,NO2à-N,NO3à-N,PO43à-P,COD and VFAs concentrations were23.1, 1.6,0.2, 2.2,130.5and82.9mg/L, respectively,with initial PHAs and Gly of7.3and14.2mmolC/L (Fig.4).
In the anaerobic stage(150min),COD and VFAs gradually decreased to46.6and3.0mg/L,respectively,followed by PHAs and PO43à-P increasing to13.8mmolC/L and24.3mg/L,respec-tively,and Gly decreasing to8.7mg/L.PO43à-P release mainly hap-pened in the?rst90min,while COD,VFAs,PHAs and Gly kept changing throughout the anaerobic stage,indicating that both PAOs and GAOs participated in the transformation of extracellular COD to intracellular PHAs(mainly PHB,Fig.4B).Additionally,NH4+-N and NO3à-N almost unchanged in the anaerobic stage,but NO2à-N rapidly decreased to0.5mg/L in the?rst15min(Fig.4A).The low NO2à-N denitri?cation amount(1.1mg/L)led to high amount of COD stored as intracellular carbons by PAOs and GAOs(COD intra ef?ciency was97.8%).
In the aerobic stage(180min),COD maintained at about
45.5mg/L,with VFAs maintained at around zero.PO43à-P gradually
decreased to0.4mg/L,followed by PHAs decreasing to8.2mmolC/ L and Gly increasing to12.7mmolC/L.NH4+-N gradually decreased to1.4mg/L,accompanied by the production of NO2à-N and NO3à-N
(5.0and 2.3mg/L,respectively),with a total nitrogen loss of
13.1mg/L.The results indicated the simultaneous N and P removal
through SNDPR by PAOs with/without DGAOs using the intracellu-lar stored PHAs,since almost no VFAs was left for denitrifying OHOs to conduct exogenous denitri?cation.
In the subsequent anoxic stage(120min),COD,PO43à-P and NH4+-N were almost unchanged,and VFAs remained at zero.
NO2à-N and NO3à-N gradually decreased to2.1and0.3mg/L,respec-tively,accompanied by the degradation of PHAs and the composi-tion of Gly(Fig.4A).The results con?rmed the possibility of combing SNDPR with post-denitri?cation for further N removal improvement.
3.4.Con?rming the enhanced nutrient removal by the activities of
PAOs,GAOs,AOB and NOB
Activities of functional microorganisms(e.g.PAOs,DPAOs, AGAOs,DGAOs,AOB and NOB)in the simultaneous N and P removal in a typical cycle on day112was determined based on a stoichiometry methodology reported previously(Wang et al., 2016)(Table3).
In the anaerobic stage,PRA and COD intra were22.2and136.4mg/ L,respectively.Proportion of PAOs contributed in COD intra(P PAO,An) was33.6%as calculated by0.5P PAO,An=PRA/COD intra(Wang et al., 2016)while GAOs contributed to66.4%.Proportion of PAOs con-tributed in D PHAs was26.6%(1.33molC/molC?33.6%?(1.33 molC/molC?33.6%+1.86molC/molC?66.4%),where 1.33and
1.86molC/molC were the PHAs/COD intra value for the PAOs model
and GAOs model,respectively(Smolders et al.,1995;Zeng et al., 2003b))with GAOs contributing up to73.4%.Proportion of PAOs contributed in D Gly was18.4%(0.5molC/molC?33.6%?
(0.5molC/molC?33.6%+1.12?66.4%),where0.5and1.12molC/-
molC were the Gly/COD intra value for the PAOs model and GAOs model,respectively(Smolders et al.,1995;Zeng et al.,2003b))with GAOs contributing up to81.6%.
In the aerobic stage,PO43à-P was totally removed with a PUA of
0.77mmolP/L(23.8mg/L,Fig.4A).D TIN(inorganic nitrogen loss)
was13.1mg/L,with D PHAs and D Gly of5.6and4.1mmolC/L, respectively.Proportions of APAOs,DPAOs via nitrite(DPAO Ni) and DPAOs via nitrate(DPAO Na)in P removal were calculated in -proteobacterial
AOB specific
Nitrosomonas
X.Wang et al./Bioresource Technology220(2016)17–2521
Eq.(I)based on their stoichiometric models (where 0.41,0.2and 0.15in molP/molC were the PUA/D PHAs values for APAOs,DPAO Ni and DPAO Na ,respectively (Smolders et al.(1995)and Fig.S3)):0:15D PHA DPAO ;Na i t0:2D PHA DPAO ;Ni t0:41D PHA APAO ?PUA ?0:77D PHA DPAO ;Ni tD PHA DPAO ;Na tD PHA AGAO ;A ?D PHA PAO ?2:10:31D PHA DPAO ;Ni t0:35D PHA DPAO ;Na t0:42D PHA APAO ;A ?D Gly PAO ?0:85
8><>:
eI T
where,D PHA PAO ,D PHA APAO ,D PHA DPAO,Ni and D PHA DPAO,Na in mmolC/L were the D PHAs driven by PAOs,APAOs,DPAO Ni and DPAO Na ,respectively;D Gly PAO in mmolC/L was the D Gly driven by PAOs.
Thus,it could be calculated that:
D PHA APAO ;A ?1:67D PHA DPAO ;Ni ?0:4D PHA DPAO ;Na ?0:04
8><>:
D Gly APAO ;A ?0:70D Gly DPAO ;Ni ?0:14D Gly DPAO ;Na ?0:018><>:
PUA APAO ;A ?0:68PUA DPAO ;Ni ?0:08PUA DPAO ;Na ?0:01
8><>:
Therefore,88.8%of PO 43à
-P was removed by APAOs,with 10.4%removed by DPAO Ni and 0.8%removed by DPAO Na (Table 3).Addi-tionally,0.1mg/L of NO 3à-N and 1.5mg/L of NO 2à
-N was removed by DPAOs as calculated by Coma et al.(2010)and Kerrn-Jespersen and Henze (1993).
The amount of D TIN consumed for bacteria growth was esti-mated according to Zeng et al.(2003a)and Wang et al.(2016).The SRT and average MLVSS of the SNDPR-SBR system in phase 4were 12d and 2.0g/L,and Gly and PHAs stored in the biomass con-tributed to 21%of MLVSS,with active biomass wasted per cycle of $43.8mg/L.Thus, 2.2mg/L of NH 4+-N
(43.8mg/L ?24.4g/-mol ?0.22mol ?14g/mol ?450min ?180min)was used for growth with an average active biomass formula for the enriched PAOs and GAOs cultures of CH 1.91O 0.46N 0.22(Zeng et al.,2003b ).9.3mg/L of D TIN was consumed by DGAOs,accompanied by 3.5mmolC/L of D PHAs and 3.2mmolC/L of D Gly.Proportions of DGAOs via nitrite (DGAO Ni )and via nitrate (DGAO Na )in N removal were calculated in Eq.(II)based on their stoichiometric models (Wang et al.,2016).
0:28D PHA DGAO ;A ;Ni t0:13D PHA DGAO ;A ;Na ?0:66D PHA AGAO ;A tD PHA DGAO ;A ;Ni tD PHA DGAO ;A ;Na ?3:50:95D PHA AGAO ;A t1:04D PHA DGAO ;A ;Ni t0:62D PHA DGAO ;A ;Na ?3:2
8><>:
eII T
It could be calculated that:
D PHA AGAO ;A ?0:66D PHA DGAO ;A ;Ni ?1:97D PHA DGAO ;A ;Na ?0:878><>:
D Gly AGAO ;A ?0:61D Gly DGAO ;A ;Ni ?2:05D Gly DGAO ;A ;Na ?0:548><>:
D TIN DGAO ;A ;Ni ?0:55D TIN DGAO ;A ;Na ?0:11
Therefore,7.7mg/L of D TIN was removed by DGAOs via nitrite with 1.6mg/L via nitrate,indicating that 66%of NH 4+-N was removed via PNED (Table 3).PNED saved 44.3%intracellular car-bon consumption for further N removal at the subsequent anoxic stage.
In the anoxic stage,3.2mg/L of NO 2à-N and 2.2mg/L of NO 3à
-N were removed by DGAOs (Table 3),resulting in ef?uent NO 2à-N
and NO 3à
-N concentrations of 2.1and 0.3mg/L,respectively (Fig.4A).PHAs decreased by 2.0mmolC/L,accompanied by Gly
Table 2
Variations of C,N and P removal performance in 4phases over 115-day operational period.Phase
Ef?uents (mg/L)Removal ef?ciency (%)PRA (mg/L)SND ef?ciency (%)COD intra ef?ciency (%)
COD
NH 4+-N NO 2à-N NO 3à-N PO 43à-P
COD NH 4+-N TN PO 43à-P
143.5 2.10.310.80.3
80.9
96.677.295.124.746.781.1243.77.1 2.1 5.50.382.487.973.794.825.457.989.9348.1 1.7 4.6 4.40.479.697.381.693.022.859.988.04
41.5
1.2
0.2
2.4
0.386.9
97.5
92.1
93.923.059.696.2
22X.Wang et al./Bioresource Technology 220(2016)17–25
increased by1.55mmolC/L.Both of them were very close to the theoretical values for the DGAOs model(D PHAs: 2.0mmolC/L;
D Gly:1.59mmolC/L)(Wang et al.,2016),indicating that post-denitri?cation was mainly driven by PHAs.
Moreover,activities of functional microorganisms in phase1 and4were compared to interpret the enhanced nutrient removal performance(Fig.5).In phase1(day1),the contribution of AGAOs in Gly composition accounted for16.8%,with DGAOs and PAOs contributing up to65%and18.2%,respectively.In phase4(day 112),AGAOs activity decreased by almost40%,followed by DGAOs activity increased by15%(specially,DGAO Ni activity increased by 58%).The half reduced AGAOs activity represented that more intra-cellular carbons were saved for N removal via endogenous denitri?cation.
In phase1,the contribution of DGAO Ni in endogenous denitri?-cation accounted for55.4%,with DPAOs and DGAO Na contributing up to21.9%and22.7%,respectively.In phase4,the contribution of DGAO Ni activity increased to66.8%,followed by DPAOs activity decreased by almost60%and DGAO Na activity stably maintained at23%(Fig.5).The results indicated that the contribution of NOB in ammonia oxidation decreased by40.6%(form64.6%in phase 1–24%in phase4),and the emergence of partial nitri?cation-endogenous denitri?cation ensured N removal from wastewater with low C/N https://www.sodocs.net/doc/5117823863.html,pared with phase1,the contribution of APAOs in P uptake increased by4.9%in phase4,with DPAOs con-tributions decreased from15.1–11.2%(Fig.5),con?rming that APAOs activity was not affected by low DO concentration (0.5±0.1mg/L,Table1).Thereby,the nutrient removal perfor-mance of SNDPR-PD system was improved by reducing the activi-ties of AGAOs and NOB but enhancing the activities of DGAOs and APAOs.The regulated activities of functional microorganisms ensured the ef?uent PO43à-P and TN concentrations of the SNDPR-PD system stably below0.5and5.0mg/L,respectively. 3.5.Importance of combining SNDPR with post-denitri?cation for low C/N wastewater treatment
Anaerobic/aerobic operated SNDPR process possessed the advantages of both EBPR and SND,which enabled simultaneous N and P removal from low C/N wastewater(Wang et al.,2015, 2016).By comparing the nutrient removal performance of the anaerobic/aerobic/anoxic(A/O/A)operated SNDPR-PD system with other related systems,the importance of combing SNDPR with post-denitri?cation for deep-level nutrient removal was demon-strated(Table4).
The P removal performance of the SNDPR-PD system was simi-lar with A/O operated EBPRs(Miao et al.,2014;Pijuan et al.,2010), A/O/A operated PD system(Coats et al.,2011),modi?ed UCTs(Ge et al.,2013;Vaiopoulou and Aivasidis,2008)and A/O operated?oc SNDPRs(Coma et al.,2012;Wang et al.,2015),but higher than A/A/ O operated denitrifying phosphorus removal(DnPR)system (Carvalho et al.,2007)and A/O operated SNDPRs inoculated with bio?lm(Yang et al.,2010)or aerobic granular sludge(Bassin et al.,2012).Additionally,PUR of the SNDPR-PD system was similar with A/O operated EBPRs(Miao et al.,2014;Pijuan et al.,2010),A/ O/A operated PD system(Coats et al.,2011),and A/O operated SNDPRs inoculated with?oc(Coma et al.,2012;Wang et al., 2015)or bio?lm(Yang et al.,2010),but higher than A/A/O operated DnPR systems(Carvalho et al.,2007),modi?ed UCTs(Ge et al., 2013;Vaiopoulou and Aivasidis,2008)and A/O operated granular sludge SNDPR system(Bassin et al.,2012).Thereby,P removal at the aerobic stage of?oc SNDPR systems(even those with low DO concentrations,Table4)was mainly achieved by aerobic P uptake, since anoxic PURs are generally reported to be much lower than aerobic PURs(Bassin et al.,2012;Chung et al.,2006;Hu et al., 2002).APAOs activity in?oc SNDPR systems was barely affected by DO concentration,which ensured the ef?cient P removal perfor-mance via aerobic P uptake.However,adding granular sludge or bio?lm in SNDPRs enhanced the performance of denitrifying P uptake but reduced the performance of aerobic P uptake by provid-ing anoxic zone and aerobic zone(de Kreuk et al.,2005),leading to low PURs(Table4).Moreover,anoxic conditions could also be used to retain phosphorus in sludge as aerobic conditions(Ge et al., 2013;Hu et al.,2002),due to the residual NOxà.
The SND ef?ciency of the SNDPR-PD system(59.6%)was higher than A/O operated SND system(16.7%,Lo et al.,2010)and SNDPRs (49.3%,Wang et al.,2015),but lower than A/O operated SNDPRs inoculated with bio?lm(75%,Yang et al.,2010)or aerobic granular sludge(75%,Bassin et al.,2012)(Table4).The results indicated that both low DO concentration control and bio?lm/granular sludge inoculation could bene?t SND in?oc SNDPRs.
Table3
Activities of functional microorganisms in the N and P removal in a typical operation cycle on day112(phase4).
Microorganisms Anaerobic stage Aerobic stage Anoxic stage Contribution of each functional
microorganism(%)
COD intra (mg/L)PRA
(mg/L)
PUA
(mg/L)
D TIN
(mg/L)
D PHAs
(mmolC/L)
D Gly
(mmolC/L)
D TIN
(mg/L)
D PHAs
(mmolC/L)
D Gly
(mmolC/L)
P
uptake
N
removal
NH4+-N
oxidation
APAOs45.822.221.1– 1.670.7–––88.8––
DPAO Ni 2.5 1.50.40.1410.48.1
DPAO Na0.20.10.040.010.80.5
AGAOs90.6–––0.660.61––––––
DGAO Ni––7.7 1.97 2.05 3.20.80.84–58.9
DGAO Na–– 1.60.870.54 2.2 1.20.71–20.6
NOB–––––––––24
Cell growth––– 2.2–––––11.9–
Total136.422.223.813.1 5.6 4.05 5.4 2.0 1.55100100–
X.Wang et al./Bioresource Technology220(2016)17–2523
The TN removal ef?ciency of the SNDPR-PD system(92.1%)was
a little lower than A/O/A operated PD SBRs(97%,Coats et al.,2011;
98.3%,Li et al.,2014),but much higher than other related systems (Table4).Moreover,the operation duration and DO concentration needed in the SNDPR-PD system were about30%–75%lower than other systems(Bassin et al.,2012;Coats et al.,2011;Vaiopoulou and Aivasidis,2008;Wang et al.,2015)(Table4).Therefore,sub-stantial energy was saved in the SNDPR-PD system.
Consequently,post-dentitri?cation addition could improve N removal in SNDPRs.The reason was the reduced ef?uent NO Xàcon-centration,which,in turn,increased the anaerobic intracellular carbon storage to implement SNDPR-PD for low C/N wastewater treatment without external carbon addition.However,further studies are still needed to help the overall evaluation for selecting in practice such a process,such as the effect of wastewater quan-tity,operating duration,in?uent C/N ratio and phosphorus load on nutrient removal ef?ciency.
4.Conclusions
A SNDPR-PD process was successfully demonstrated for deep-level nutrient removal from low C/N ratio(3.5)wastewater without external carbon https://www.sodocs.net/doc/5117823863.html,bined control of anaero-bic/aerobic/anoxic durations and low DO inhibition to AGAOs and NO
B conducted PNED(66%)and saved44.3%more PHAs for post-denitri?cation.SNDPR achieved98.3%PO43à-P and59.0%TN removal at low DO concentrations(0.5±0.1mg/L),and post-denitri?cation further reduced25.4%TN anoxically using the residual PHAs.After115-day,the average ef?uent PO43à-P and TN concentrations were0.4and 3.9mg/L,respectively.Suf?cient utilization of PHAs in GAOs was the key for deep-level nutrient removal via SNDPR-PD.
Acknowledgements
This research was?nancially supported by Natural Science Foundation of China(51570184),and the funded project of Beijing Municipal Education Commission.Appendix A.Supplementary data
Supplementary data associated with this article can be found,in the online version,at https://www.sodocs.net/doc/5117823863.html,/10.1016/j.biortech.2016.06. 132.
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脐带间充质干细胞的研究进展 间充质干细胞（mesenchymal stem cells,MSC S ）是来源于发育早期中胚层 的一类多能干细胞[1-5]，MSC S 由于它的自我更新和多项分化潜能，而具有巨大的 治疗价值 ,日益受到关注。MSC S 有以下特点：(1)多向分化潜能，在适当的诱导条件下可分化为肌细胞[2]、成骨细胞[3、4]、脂肪细胞、神经细胞[9]、肝细胞[6]、心肌细胞[10]和表皮细胞[11, 12]；(2)通过分泌可溶性因子和转分化促进创面愈合；(3) 免疫调控功能，骨髓源（bone marrow ）MSC S 表达MHC-I类分子，不表达MHC-II 类分子，不表达CD80、CD86、CD40等协同刺激分子，体外抑制混合淋巴细胞反应，体内诱导免疫耐受[11, 15]，在预防和治疗移植物抗宿主病、诱导器官移植免疫耐受等领域有较好的应用前景；(4)连续传代培养和冷冻保存后仍具有多向分化潜能，可作为理想的种子细胞用于组织工程和细胞替代治疗。1974年Friedenstein [16] 首先证明了骨髓中存在MSC S ，以后的研究证明MSC S 不仅存在于骨髓中，也存在 于其他一些组织与器官的间质中：如外周血[17]，脐血[5]，松质骨[1, 18]，脂肪组织[1]，滑膜[18]和脐带。在所有这些来源中，脐血(umbilical cord blood)和脐带(umbilical cord)是MSC S 最理想的来源，因为它们可以通过非侵入性手段容易获 得，并且病毒污染的风险低，还可冷冻保存后行自体移植。然而，脐血MSC的培养成功率不高[19, 23-24]，Shetty 的研究认为只有6%，而脐带MSC的培养成功率可 达100%[25]。另外从脐血中分离MSC S ，就浪费了其中的造血干/祖细胞(hematopoietic stem cells/hematopoietic progenitor cells,HSCs/HPCs) [26, 27]，因此，脐带MSC S (umbilical cord mesenchymal stem cells, UC-MSC S )就成 为重要来源。 一．概述 人脐带约40 g, 它的长度约60–65 cm, 足月脐带的平均直径约1.5 cm[28, 29]。脐带被覆着鳞状上皮，叫脐带上皮，是单层或复层结构，这层上皮由羊膜延续过来[30, 31]。脐带的内部是两根动脉和一根静脉，血管之间是粘液样的结缔组织，叫做沃顿胶质，充当血管外膜的功能。脐带中无毛细血管和淋巴系统。沃顿胶质的网状系统是糖蛋白微纤维和胶原纤维。沃顿胶质中最多的葡萄糖胺聚糖是透明质酸，它是包绕在成纤维样细胞和胶原纤维周围的并维持脐带形状的水合凝胶，使脐带免受挤压。沃顿胶质的基质细胞是成纤维样细胞[32]，这种中间丝蛋白表达于间充质来源的细胞如成纤维细胞的，而不表达于平滑肌细胞。共表达波形蛋白和索蛋白提示这些细胞本质上肌纤维母细胞。 脐带基质细胞也是一种具有多能干细胞特点的细胞，具有多项分化潜能，其 形态和生物学特点与骨髓源性MSC S 相似[5, 20, 21, 38, 46]，但脐带MSC S 更原始，是介 于成体干细胞和胚胎干细胞之间的一种干细胞，表达Oct-4, Sox-2和Nanog等多
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型性格。3．其它：精神分裂症发病与年龄有一定关系，多发生于青壮年，约1/2患者于20～30岁发病。发病年龄与临床类型有关，偏执型发病较晚，有资料提示偏执型平均发病年龄为35岁，其它型为23岁。80年代国内12地区调查资料：女性总患病率（7.07%。）与时点患病率（5.91%。）明显高于男性（4.33%。与3.68%。）。Kretschmer在描述性格与精神分裂症关系时指出：61%患者为瘦长型和运动家型，12.8%为肥胖型，11.3%发育不良型。在躯体疾病或分娩之后发生精神分裂症是很常见的现象，可能是心理性生理性应激的非特异性影响。部分患者在脑外伤后或感染性疾病后发病；有报告在精神分裂症患者的脑脊液中发现病毒性物质；月经期内病情加重等躯体因素都可能是诱发因素，但在精神分裂症发病机理中的价值有待进一步证实。（二）心理社会因素1．环境因素①家庭中父母的性格，言行、举止和教育方式（如放纵、溺爱、过严）等都会影响子女的心身健康或导致个性偏离常态。②家庭成员间的关系及其精神交流的紊乱。③生活不安定、居住拥挤、职业不固定、人际关系不良、噪音干扰、环境污染等均对发病有一定作用。农村精神分裂症发病率明显低于城市。2．心理因素一般认为生活事件可发诱发精神分裂症。诸如失学、失恋、学习紧张、家庭纠纷、夫妻不和、意处事故等均对发病有一定影响，但这些事件的性质均无特殊性。因此，心理因素也仅属诱发因
脐带血造血干细胞库管理办法(试行)
脐带血造血干细胞库管理办法（试行） 第一章总则 第一条为合理利用我国脐带血造血干细胞资源，促进脐带血造血干细胞移植高新技术的发展，确保脐带血 造血干细胞应用的安全性和有效性，特制定本管理办法。 第二条脐带血造血干细胞库是指以人体造血干细胞移植为目的，具有采集、处理、保存和提供造血干细胞 的能力，并具有相当研究实力的特殊血站。 任何单位和个人不得以营利为目的进行脐带血采供活动。 第三条本办法所指脐带血为与孕妇和新生儿血容量和血循环无关的，由新生儿脐带扎断后的远端所采集的 胎盘血。 第四条对脐带血造血干细胞库实行全国统一规划，统一布局，统一标准，统一规范和统一管理制度。 第二章设置审批 第五条国务院卫生行政部门根据我国人口分布、卫生资源、临床造血干细胞移植需要等实际情况，制订我 国脐带血造血干细胞库设置的总体布局和发展规划。 第六条脐带血造血干细胞库的设置必须经国务院卫生行政部门批准。 第七条国务院卫生行政部门成立由有关方面专家组成的脐带血造血干细胞库专家委员会（以下简称专家委
员会），负责对脐带血造血干细胞库设置的申请、验收和考评提出论证意见。专家委员会负责制订脐带血 造血干细胞库建设、操作、运行等技术标准。 第八条脐带血造血干细胞库设置的申请者除符合国家规划和布局要求，具备设置一般血站基本条件之外， 还需具备下列条件： （一）具有基本的血液学研究基础和造血干细胞研究能力； （二）具有符合储存不低于1 万份脐带血的高清洁度的空间和冷冻设备的设计规划； （三）具有血细胞生物学、HLA 配型、相关病原体检测、遗传学和冷冻生物学、专供脐带血处理等符合GMP、 GLP 标准的实验室、资料保存室； （四）具有流式细胞仪、程控冷冻仪、PCR 仪和细胞冷冻及相关检测及计算机网络管理等仪器设备； （五）具有独立开展实验血液学、免疫学、造血细胞培养、检测、HLA 配型、病原体检测、冷冻生物学、 管理、质量控制和监测、仪器操作、资料保管和共享等方面的技术、管理和服务人员； （六）具有安全可靠的脐带血来源保证； （七）具备多渠道筹集建设资金运转经费的能力。 第九条设置脐带血造血干细胞库应向所在地省级卫生行政部门提交设置可行性研究报告，内容包括：
公文文体翻译的特点
一、公文的文体特点及翻译 （一）公文的文体特点 公文主要包括政府发布的各种公告、宣言、声明、规章法令、通告、启示和各类法律文件。其文体特点主要体现在以下几方面： 1）措词准确。发布公文的目的一般在于解释或阐明公文发布者的立场、观点或政策、措施，因此公文在措词上必须准确明晰，切忌模棱两可或含糊晦涩。 2）用词正式，且多古体词。公文作为政府或职能部门所发布的文章，需具有其权威性、规范性。因此在用词上一般较为正式，并且不排除使用一些较为古雅的词（如hereinafter, hereof, herewith等等）。 3）普通词多有特定意义。许多普通的词在公文体中常常具有其特定的意义。如allowance一词通常指"允许"、"津贴"，而在经贸合同中则多指"折扣"。 4）长句、复杂句较多。公文体为使其逻辑严谨，表意准确，在句法上常常叠床架屋，以至使得句式有时显得臃肿迟滞，同时句子的长度也大为增加。 （二）公文的翻译 翻译公文首先要注意公文特有的形式，包括格式、体例等。对已模式化、程式化的格式译者决不应随便更改。其次，译者应透彻理解原文，特别是要正确把握原文词义，认清一些common words在公文中特有的含义。再次，在措词上必须使译文的语体与原文相适应。一般说来，英语公文翻译通常应使用正式书面语体，并酌情使用某些文言连词或虚词。最后，公文翻译中要注意长句的处理。要在理清句意和各部分之间逻辑关系的前提下恰当使用切分法或语序调整法，以使译文通畅、自然、地道。 二、商贸函电的文体特点及翻译 （一）商贸函电的文体特点 商贸函电指经济贸易活动中的各类信函、电报、电传等。其文体特征主要有： 1）措词简洁明了。为使表达明晰，商贸函电在措词上力求简明扼要，不太讲究修饰。 2）用语正式庄重。正式庄重的语言常常显得诚恳、自然、有礼貌，因此常用于商贸函电中。
精神分裂症的发病原因是什么
精神分裂症的发病原因是什么 精神分裂症是一种精神病，对于我们的影响是很大的，如果不幸患上就要及时做好治疗，不然后果会很严重，无法进行正常的工作和生活，是一件很尴尬的事情。因此为了避免患上这样的疾病，我们就要做好预防，今天我们就请广州协佳的专家张可斌来介绍一下精神分裂症的发病原因。 精神分裂症是严重影响人们身体健康的一种疾病，这种疾病会让我们整体看起来不正常，会出现胡言乱语的情况，甚至还会出现幻想幻听，可见精神分裂症这种病的危害程度。 (1)精神刺激：人的心理与社会因素密切相关，个人与社会环境不相适应，就产生了精神刺激，精神刺激导致大脑功能紊乱，出现精神障碍。不管是令人愉快的良性刺激，还是使人痛苦的恶性刺激，超过一定的限度都会对人的心理造成影响。 (2)遗传因素：精神病中如精神分裂症、情感性精神障碍，家族中精神病的患病率明显高于一般普通人群，而且血缘关系愈近，发病机会愈高。此外，精神发育迟滞、癫痫性精神障碍的遗传性在发病因素中也占相当的比重。这也是精神病的病因之一。 (3)自身：在同样的环境中，承受同样的精神刺激，那些心理素质差、对精神刺激耐受力低的人易发病。通常情况下，性格内向、心胸狭窄、过分自尊的人，不与人交往、孤僻懒散的人受挫折后容易出现精神异常。 (4)躯体因素：感染、中毒、颅脑外伤、肿瘤、内分泌、代谢及营养障碍等均可导致精神障碍，。但应注意，精神障碍伴有的躯体因素，并不完全与精神症状直接相关，有些是由躯体因素直接引起的，有些则是以躯体因素只作为一种诱因而存在。 孕期感染。如果在怀孕期间，孕妇感染了某种病毒，病毒也传染给了胎儿的话，那么，胎儿出生长大后患上精神分裂症的可能性是极其的大。所以怀孕中的女性朋友要注意卫生，尽量不要接触病毒源。 上述就是关于精神分裂症的发病原因，想必大家都已经知道了吧。患上精神分裂症之后，大家也不必过于伤心，现在我国的医疗水平是足以让大家快速恢复过来的，所以说一定要保持良好的情绪。
第六章 相关函数的估计
6. 相关函数的估计（循环相关） 6.1. 相关函数与协方差函数 6.1.1. 自相关函数和自协方差函数 1、 自相关和自协方差函数的定义 相关函数是随机信号的二阶统计特征，它表示随机信号不同时刻取值的关联程度。 设随机信号)(t x 在时刻j i t t ,的取值是j i x x ,，则自相关函数的定义为 j i j i j i j i N n n j n i N j i j i x dx dx t t x x f x x x x N x x E t t R ??∑= ===∞ →),;,(1lim ] [),(1 ) ()( 式中，上角标“（n ）”是样本的序号。 自协方差函数的定义与自相关函数的定义相似，只是先要减掉样本的均值函数再求乘积的数学期望。亦即： j i j i j i x j x i N n x n j x n i N x j x i j i x dx dx t t x x f m x m x m x m x N m x m x E t t C j i j i j i ??∑--= --=--==∞ →),;,())(() )((1lim )] )([(),(1 ) ()( 当过程平稳时，);,(),;,(τj i j i j i x x f t t x x f =。这时自相关函数和自协方差函数只是i j t t -=τ的函数，与j i t t ,的具体取值无关，因此可以记作)(τx R 和)(τx C 。 对于平稳且各态历经的随机信号，又可以取单一样本从时间意义上来求这些统计特性： 时间自相关函数为：
? + - ∞ →+=22 )()(1lim )(T T T x dt t x t x T R ττ 时间自协方差函数为： ? + - ∞ →-+-=22 ])(][)([1lim )(T T x x T x dt m t x m t x T C ττ 在信号处理过程中，有时会人为地引入复数信号。此时相应的定义变成 ][),(* j i j i x x x E t t R = )]()[(),(* j i x j x i j i x m x m x E t t C --= 式中，上角标*代表取共轭。 2、 自相关和自协方差函数的性质 自相关和自协方差函数的主要性质如下： （1） 对称性 当)(t x 时实函数时，)(τx R 和)(τx C 是实偶函数。即 ) ()(), ()()()(),()(* * ττττττττx x x x x x x x C C R R C C R R =-=-== 当)(t x 时复值函数时，)(τx R 和)(τx C 具有共轭对称性。即 )()(), ()(* * ττττx x x x C C R R =-=- （2） 极限值 )(, )()0(,)0(2=∞=∞==x x x x x x x C m R C D R σ （3） 不等式 当0≠τ时， )()0(), ()0(ττx x x x C C R R ≥≥ 因此， )0()()(x x x R R ττρ=
精神分裂症的病因是什么
精神分裂症的病因是什么 精神分裂症是一种精神方面的疾病，青壮年发生的概率高，一般 在16～40岁间，没有正常器官的疾病出现，为一种功能性精神病。 精神分裂症大部分的患者是由于在日常的生活和工作当中受到的压力 过大，而患者没有一个良好的疏导的方式所导致。患者在出现该情况 不仅影响本人的正常社会生活，且对家庭和社会也造成很严重的影响。 精神分裂症常见的致病因素： 1、环境因素：工作环境比如经济水平低低收入人群、无职业的人群中，精神分裂症的患病率明显高于经济水平高的职业人群的患病率。还有实际的生活环境生活中的不如意不开心也会诱发该病。 2、心理因素：生活工作中的不开心不满意，导致情绪上的失控，心里长期受到压抑没有办法和没有正确的途径去发泄，如恋爱失败， 婚姻破裂，学习、工作中不愉快都会成为本病的原因。 3、遗传因素：家族中长辈或者亲属中曾经有过这样的病人，后代会出现精神分裂症的机会比正常人要高。 4、精神影响：人的心里与社会要各个方面都有着不可缺少的联系，对社会环境不适应，自己无法融入到社会中去，自己与社会环境不相
适应，精神和心情就会受到一定的影响，大脑控制着人的精神世界， 有可能促发精神分裂症。 5、身体方面：细菌感染、出现中毒情况、大脑外伤、肿瘤、身体的代谢及营养不良等均可能导致使精神分裂症，身体受到外界环境的 影响受到一定程度的伤害，心里受到打击，无法承受伤害造成的痛苦，可能会出现精神的问题。 对于精神分裂症一定要配合治疗，接受全面正确的治疗，最好的 疗法就是中医疗法加心理疗法。早发现并及时治疗并且科学合理的治疗，不要相信迷信，要去正规的医院接受合理的治疗，接受正确的治 疗按照医生的要求对症下药，配合医生和家人，给病人创造一个良好 的治疗环境，对于该病的康复和痊愈会起到意想不到的效果。
卫生部办公厅关于印发《脐带血造血干细胞治疗技术管理规范(试行)
卫生部办公厅关于印发《脐带血造血干细胞治疗技术管理规 范(试行)》的通知 【法规类别】采供血机构和血液管理 【发文字号】卫办医政发[2009]189号 【失效依据】国家卫生计生委办公厅关于印发造血干细胞移植技术管理规范(2017年版)等15个“限制临床应用”医疗技术管理规范和质量控制指标的通知 【发布部门】卫生部(已撤销) 【发布日期】2009.11.13 【实施日期】2009.11.13 【时效性】失效 【效力级别】部门规范性文件 卫生部办公厅关于印发《脐带血造血干细胞治疗技术管理规范（试行）》的通知 （卫办医政发〔2009〕189号） 各省、自治区、直辖市卫生厅局，新疆生产建设兵团卫生局： 为贯彻落实《医疗技术临床应用管理办法》，做好脐带血造血干细胞治疗技术审核和临床应用管理，保障医疗质量和医疗安全，我部组织制定了《脐带血造血干细胞治疗技术管理规范（试行）》。现印发给你们，请遵照执行。 二〇〇九年十一月十三日
脐带血造血干细胞 治疗技术管理规范（试行） 为规范脐带血造血干细胞治疗技术的临床应用，保证医疗质量和医疗安全，制定本规范。本规范为技术审核机构对医疗机构申请临床应用脐带血造血干细胞治疗技术进行技术审核的依据，是医疗机构及其医师开展脐带血造血干细胞治疗技术的最低要求。 本治疗技术管理规范适用于脐带血造血干细胞移植技术。 一、医疗机构基本要求 （一）开展脐带血造血干细胞治疗技术的医疗机构应当与其功能、任务相适应，有合法脐带血造血干细胞来源。 （二）三级综合医院、血液病医院或儿童医院，具有卫生行政部门核准登记的血液内科或儿科专业诊疗科目。 1.三级综合医院血液内科开展成人脐带血造血干细胞治疗技术的，还应当具备以下条件： （1）近3年内独立开展脐带血造血干细胞和（或）同种异基因造血干细胞移植15例以上。 （2）有4张床位以上的百级层流病房，配备病人呼叫系统、心电监护仪、电动吸引器、供氧设施。 （3）开展儿童脐带血造血干细胞治疗技术的，还应至少有1名具有副主任医师以上专业技术职务任职资格的儿科医师。 2.三级综合医院儿科开展儿童脐带血造血干细胞治疗技术的，还应当具备以下条件：
VB第六章习题答案(上海立信会计学院)
上海立信会计学院 班级：学号: 姓名：指导教师: 专业: 习题六p150 -、简述子过程与函数过程的共同点和不同之处。 答：相同之处：都是功能相对独立的一种子程序结构，它们有各自的过程头、变量声明和过程体，在程序的设计过程中可以提高效率。 不同之处: (1)声明的关键字不同。子过程为Sub,而函数过程为 Funct ion。 (2)了过程无值就无类型说明，函数过程有值因此有类型的说明 (3)函数的过程名称同时是结果变量，因此在函数过程体 内至少要对函数的过程名赋值一次数据，而子过程内不能赋 值。
(4)调用的方式不同，子过程是一条独立的语句，可以用 Cal I子过程名或省略Call直接以子过程名调用；函数的过 程不是一条独立的语句，是一个函数值，必须参与表达式运算。(5)通常，函数过程可以被子过程代替，只需要在调用的 过程中改变一下过程调用的形式，并在子过程的形参表中增加一个地址传递的形参来传递结果。 二、什么是形参，实参？什么是值引用？地址引用？地址应用 对实参有什么限制？ 答：形参：在定义过程时的一种假设的参数，只代表该过程的参数的个数、类型，它的名字不重要，没有任何的值, 只表示在过程体内将进行的一种操作。 实参：在调用子过程时提供过程形参的初始值，或通过过程体处理后的结果。 值引用：系统将实际参数的值传到形参之后，实参与形参断开联系，过程中对于形参的修改不会影响到实际参数的变化。 地址引用：实参与形参共同使用一个存储单元，在过程中对形参进行修改，则对应的实际参数也同时变化。
在地址引用时，实参只能是变量，不能是常量或表达式。
三、指出下面过程语句说明中的错误: Sub f1 (n%) as Integer Function f1%(f1%) Sub fl (ByVa I n% 0) Sub fl(X(i) as Integer) 答：(1) Sub子过程名没有返回值，因此就没有数据的类型 (2)函数名与形参名称相同 (3)形参n为数组，不允许声明为By Vai值传递 (4)形参x(i)不允许为数组元素 四、已知有如下求两个平方数和的fsum子过程: Publ ic Sub fsum (sum%, ByVaI a%, ByVaI b%) sum =a*a+b*b End Sub 在事件过程中若有如下变量声明: Pr ivate Sub Commandl Cl ick()
精神分裂症应该怎么治疗
精神分裂症应该怎么治疗 1、坚持服药治疗 服药治疗是最有效的预防复发措施临床大量统计资料表明，大多数精神分裂症的复发与自行停药有关。坚持维持量服药的病人复发率为40%。而没坚持维持量服药者复发率高达80%。因此，病人和家属要高度重视维持治疗。 2、及时发现复发的先兆，及时处理 精神分裂症的复发是有先兆的，只要及时发现，及时调整药物和剂量，一般都能防止复发，常见的复发先兆为：病人无原因出现睡眠不好、懒散、不愿起床、发呆发愣、情绪不稳、无故发脾气、烦躁易怒、胡思乱想、说话离谱，或病中的想法又露头等。这时就应该及时就医，调整治疗病情波动时的及时处理可免于疾病的复发。 3、坚持定期门诊复查 一定要坚持定期到门诊复查，使医生连续地、动态地了解病情，使病人经常处于精神科医生的医疗监护之下，及时根据病情变化调整药量。通过复查也可使端正人及时得到咨询和心理治疗解除病人在生活、工作和药物治疗中的各种困惑，这对预防精神分裂症的复发也起着重要作用。 4、减少诱发因素 家属及周围人要充分认识到精神分裂症病人病后精神状态的薄弱性，帮助安排好日常的生活、工作、学习。经常与病人谈心，帮助病人正确对待疾病，正确对待现实生活，帮助病人提高心理承受能力，学会对待应激事件的方法，鼓励病人增强信心，指导病人充实生活，使病人在没有心理压力和精神困扰的环境中生活。 首先是性格上的改变，塬本活泼开朗爱玩的人，突然变得沉默寡言，独自发呆，不与人交往，爱干净的人也变的不注意卫生、生活
懒散、纪律松弛、做事注意力不集中，总是和患病之前的性格完全 相悖。 再者就是语言表达异常，在谈话中说一些无关的谈话内容，使人无法理解。连最简单的话语都无法准确称述，与之谈话完全感觉不 到重心。 第三个就是行为的异常，行为怪异让人无法理解，喜欢独处、不适意的追逐异性，不知廉耻，自语自笑、生活懒散、时常发呆、蒙 头大睡、四处乱跑，夜不归宿等。 还有情感上的变化，失去了以往的热情，开始变的冷淡、对亲人不关心、和友人疏远，对周围事情不感兴趣，一点消失都可大动干戈。 最后就是敏感多疑，对任何事情比较敏感，精神分裂症患者，总认为有人针对自己。甚至有时认为有人要害自己，从而不吃不喝。 但是也有的会出现难以入眠、容易被惊醒或睡眠不深，整晚做恶梦或者长睡不醒的现象。这些都有可能是患上了精神分裂症。 1.加强心理护理 心理护理是家庭护理中的重要方面，由于社会上普遍存在对精神病人的歧视和偏见，给病人造成很大的精神压力，常表现为自卑、 抑郁、绝望等，有的病人会因无法承受压力而自杀。家属应多给予 些爱心和理解，满足其心理需求，尽力消除病人的悲观情绪。病人 生活在家庭中，与亲人朝夕相处，接触密切，家属便于对病人的情感、行为进行细致的观察，病人的思想活动也易于向家属暴露。家 属应掌握适当的心理护理方法，随时对病人进行启发与帮助，启发 病人对病态的认识，帮助他们树立自信，以积极的心态好地回归社会。 2.重视服药的依从性 精神分裂症病人家庭护理的关键就在于要让病人按时按量吃药维持治疗。如果不按时服药，精神病尤其是精神分裂症的复发率很高。精神病人在医院经过一系统的治疗痊愈后，一般需要维持2~3年的
卫生部关于印发《脐带血造血干细胞库设置管理规范(试行)》的通知
卫生部关于印发《脐带血造血干细胞库设置管理规范(试行)》的通知 发文机关：卫生部(已撤销) 发布日期： 2001.01.09 生效日期： 2001.02.01 时效性：现行有效 文号：卫医发(2001)10号 各省、自治区、直辖市卫生厅局： 为贯彻实施《脐带血造血干细胞库管理办法（试行）》，保证脐带血临床使用的安全、有效，我部制定了《脐带血造血干细胞库设计管理规范（试行）》。现印发给你们，请遵照执行。 附件：《脐带血造血干细胞库设置管理规范（试行）》 二○○一年一月九日 附件： 脐带血造血干细胞库设置管理规范（试行） 脐带血造血干细胞库的设置管理必须符合本规范的规定。 一、机构设置 （一）脐带血造血干细胞库（以下简称脐带血库）实行主任负责制。 （二）部门设置 脐带血库设置业务科室至少应涵盖以下功能：脐带血采运、处理、细胞培养、组织配型、微生物、深低温冻存及融化、脐带血档案资料及独立的质量管理部分。 二、人员要求
（一）脐带血库主任应具有医学高级职称。脐带血库可设副主任，应具有临床医学或生物学中、高级职称。 （二）各部门负责人员要求 1．负责脐带血采运的人员应具有医学中专以上学历，2年以上医护工作经验，经专业培训并考核合格者。 2．负责细胞培养、组织配型、微生物、深低温冻存及融化、质量保证的人员应具有医学或相关学科本科以上学历，4年以上专业工作经历，并具有丰富的相关专业技术经验和较高的业务指导水平。 3．负责档案资料的人员应具相关专业中专以上学历，具有计算机基础知识和一定的医学知识，熟悉脐带血库的生产全过程。 4．负责其它业务工作的人员应具有相关专业大学以上学历，熟悉相关业务，具有2年以上相关专业工作经验。 （三）各部门工作人员任职条件 1．脐带血采集人员为经过严格专业培训的护士或助产士职称以上卫生专业技术人员并经考核合格者。 2．脐带血处理技术人员为医学、生物学专业大专以上学历，经培训并考核合格者。 3．脐带血冻存技术人员为大专以上学历、经培训并考核合格者。 4．脐带血库实验室技术人员为相关专业大专以上学历，经培训并考核合格者。 三、建筑和设施 （一）脐带血库建筑选址应保证周围无污染源。 （二）脐带血库建筑设施应符合国家有关规定，总体结构与装修要符合抗震、消防、安全、合理、坚固的要求。 （三）脐带血库要布局合理，建筑面积应达到至少能够储存一万份脐带血的空间；并具有脐带血处理洁净室、深低温冻存室、组织配型室、细菌检测室、病毒检测室、造血干/祖细胞检测室、流式细胞仪室、档案资料室、收/发血室、消毒室等专业房。 （四）业务工作区域应与行政区域分开。
翻译特点
A. Literal translation: It strives to reproduce both the ideological content and the style of the original works and retains as much as possible the figures of speech. B. Free translation Free translation changes the original work’s figures of speech, sent ence structures or patterns, but not the original meaning. C. Domestication: it refers to the target-culture-oriented translation in which unusual expressions to the target culture are exploited and turned into some familiar ones so as to make the translated text intelligible and easy for the target readers. D. Foreignization:(异化翻译)retaining something of the foreignness of the original 在一定程度上保留原文的异域性（保留原文的语言和文化差异） Her eyes sparkled with tears, her breath was soft and faint .In response, she was like a lovely flower mirrored in the water in motion, a pliant willow swaying in the wind. ___chapter three (泪光点点，娇喘微微，娴静时如姣花照水，行动处似弱柳扶风。这是林黛玉进贾府，与贾宝玉初次见面时宝玉严重的待遇形象。曹雪芹用泪光点点，娇喘微微来表现林黛玉的多愁善感，弱不经风并运用姣花照水，弱柳扶风两个比喻勾画出林黛玉娴静雅致的形象) Mr. Yang used literal translation and translated as a lovely flower mirrored in the water and a pliant willow swaying in the wind .He reserved the original form and images to reflect the image of Lin Daiyu. B. free 》translation When the images or expressions are the same with English, Mr.Yang adopt to keep the original images and made it concise and clear. (意象或表达方式意义相似则意译当原文的 意 向或表达方式在中英文中有相同的意义,并非汉语所特有,杨宪益采取意译法,并保留原文的意向.简约精炼,忠实清晰.) Examples: 例1:黛玉便说“兔死狐悲,物伤其类”,不免感叹起来。(第57回) 杨译:Daiyu exclaimed in distress and sympathy. 解析：“兔”与“狐”在中西生态文化中具有相同的含义。两种动物都是打猎的主要对象,在英语中也有fox - hunting , hare- coursing的用法。这两个意象并未包含非常重要的文化信息,所以跳脱未译,在杨译本中没有出现例3:贾瑞急的也不敢则声,只得悄悄的出来,将门撼了撼,关的铁桶一般。(第12回) 杨译: He crept out to try the gate and found it securely locked. Although Yang uses free translation in above examples, but it is quite accurate and is closed to the original version. C.Domestication 例9: (平儿) “如今这事八下里水落石出了,连前儿太太屋里丢的也有了主儿。”(第61回) 杨译:“The fact is, this business ismore or less solved; we’ve even found out as well who took the
VB第六章习题答案(上海立信会计学院)
上海立信会计学院 班级：学号：姓名：指导教师： 系部：专业： 习题六p150 一、简述子过程与函数过程的共同点和不同之处。 答：相同之处：都是功能相对独立的一种子程序结构，它们有各自的过程头、变量声明和过程体，在程序的设计过程中可以提高效率。 不同之处： （1）声明的关键字不同。子过程为Sub，而函数过程为Function。 （2）了过程无值就无类型说明，函数过程有值因此有类型的说明 （3）函数的过程名称同时是结果变量，因此在函数过程体内至少要对函数的过程名赋值一次数据，而子过程内不能赋值。 （4）调用的方式不同，子过程是一条独立的语句，可以用Call子过程名或省略Call直接以子过程名调用；函数的过程不是一条独立的语句，是一个函数值，必须参与表达式运算。 （5）通常，函数过程可以被子过程代替，只需要在调用的过程中改变一下过程调用的形式，并在子过程的形参表中增加一个地址传递的形参来传递结果。 二、什么是形参，实参？什么是值引用？地址引用？地址应用对实参有什么限制？ 答：形参：在定义过程时的一种假设的参数，只代表该过程的参数的个数、类型，它的名字不重要，没有任何的值，只表示在过程体内将进行的一种操作。 实参：在调用子过程时提供过程形参的初始值，或通过过程体处理后的结果。 值引用：系统将实际参数的值传到形参之后，实参与形参断开联系，过程中对于形参的修改不会影响到实际参数的变化。 地址引用：实参与形参共同使用一个存储单元，在过程中对形参进行修改，则对应的实际参数也同时变化。 在地址引用时，实参只能是变量，不能是常量或表达式。 三、指出下面过程语句说明中的错误：
（1）Sub f1(n%) as Integer （2）Function f1%(f1%) （3）Sub f1(ByVal n%()) （4）Sub f1(x(i) as Integer) 答：（1）Sub子过程名没有返回值，因此就没有数据的类型 （2）函数名与形参名称相同 （3）形参n为数组，不允许声明为ByVal值传递 （4）形参x(i)不允许为数组元素 四、已知有如下求两个平方数和的fsum子过程： Public Sub fsum(sum%, ByVal a%, ByVal b%) sum = a * a + b * b End Sub 在事件过程中若有如下变量声明： Private Sub Command1_Click() Dim a%, b%, c! a = 10: b = 20 则指出如下过程调用语句的错误所在： （1）fusum 3, 4, 5 （2）fsum c, a, b （3）fsum a + b, a, b （4）Call fsum(Sqr(c), Sqr(a), Sqr(b)) （5）Call fsum c,a,b 答：（1）furm子过程的第一个形参是地址传递，因此对应的实参3不能是常量 （2）furm的第一个形参是整型而且是地址传递，对应的实参c是单精度，数据类型不匹配（3）furm的第一个形参是地址传递，因此对应的实参a+b不应当是表达式 （4）furm的第一个形参是地址传递，因此对应的实参Sqr(c)不应当是表达式 （5）用Call语句调用furm子过程时，必须用圆括号来描述实参 六、要使变量在某事件过程中保留值，有哪几种变量声明的方法？ 答：声明为static或者全局变量 七、为了使某变量在所有的窗体中都能使用，应在何处声明该变量？ 答：应在窗体\模块的通用声明段用Public关键字声明为全局变量。
精神分裂症患者在怎样的情况下会自杀
精神分裂症患者在怎样的情况下会自杀 精神分裂症是最常见的一种精神病。早期主要表现为性格改变，如不理采亲人、不讲卫生、对镜子独笑等。病情进一步发展，即表现为思维紊乱，病人的思考过程缺乏逻辑性和连贯性，言语零乱、词不达意。精神分裂症患者随时有可能出现危险行为，这主要是指伤人毁物、自伤自杀和忽然出走。这些危险行为是受特定的精神症状支配的.那么精神分裂症患者在什么情况下会自杀呢？ 被害妄想：这是所有精神病人最常见的症状之一，多数病人采取忍耐、逃避的态度，少数病人也会“先下手为强”，对他的“假想敌”主动攻击。对此，最重要的是弄清病人的妄想对象，即：病人以为是谁要害他。假如病人的妄想对象是某个家里人，则应尽量让这位家属阔别病人，至少不要让他与病人单独在一起。 抑郁情绪：精神分裂症病人在疾病的不同时期，可能出现情绪低落，甚至悲观厌世。特别需要留意的是，有相当一部分自杀成功的病人，是在疾病的恢复期实施自杀行为的。病人在精神病症状消除以后，因自己的病背上了沉重的思想包袱，不能正确对待升学、就业、婚姻等现实问题，感到走投无路，因此选择了轻生。对此，家属一定要防患于未然，要尽早发现病人的心理困扰，及时疏导。 对已经明确表示出自杀观念的病人，家属既不要惊慌失措，也不要躲躲闪闪，要主动与病人讨论自杀的利弊，帮助病人全面、客观地评估现实中碰到的各种困难，找出切实可行的解决办法。 另外，这种病人在自杀之前，是经过周密考虑，并且做了充分预备的，例如写遗书、收拾旧物、向家人离别、选择自杀时间、预备自杀工具等。这类病人的自杀方式也是比较温顺的，多数是服药自杀。因此，他需要一定的时间来积攒足足数目的药物，这时就能看出由家属保管药品的重要性了。只要家属密切观察病人的情绪变化，是不难早期发现病人的自杀企图的。 药源性焦虑：抗精神病药的副作用之一是可能引起病人莫名的焦躁不安、手足无措，并伴有心慌、出汗、恐惧等。这些表现多是发作性的，多数发生在下午到傍晚时分，也有的病人在打长效针以后的2?3天内出现上述表现。这种时间上的规律性，有助于家属判定病人的焦虑情绪是否由于药物所致。病人急于摆脱这种强烈的痛苦，会出现冲动伤人或自伤，这些行为只是为了发泄和解脱，并不以死为终极目的。家属可以在病人发作时，给他服用小剂量的安定类药物，或者在医生的指导下，调整抗精神病药的剂量或品种，这样就可以有效地控制病人的焦虑发作。 极度兴奋：病人的精神症状表现为严重的思维紊乱、言语杂乱无章、行为缺乏目的性，这类病人也可能出现自伤或伤人毁物。由于病人的兴奋躁动是持续性的，家属有充分的思想预备，一般比较轻易防范。家属要保管好家里的刀、剪、火、煤气等危险物品，但最根本的办法，是使用大剂量的、具有强烈镇静作用的药物来控制病人的兴奋。假如在家里护理病人确有困难，则可以强制病人住院治
脐带血间充质干细胞的分离培养和鉴定
脐带血间充质干细胞的分离培养和鉴定 【摘要】目的分离培养脐带血间充质干细胞并检测其生物学特性。方法在无菌条件下用密度梯度离心的方法获得脐血单个核细胞，接种含10%胎牛血清的DMEM培养基中。单个核细胞行贴壁培养后，进行细胞形态学观察，绘制细胞生长曲线，分析细胞周期，检测细胞表面抗原。结果采用Percoll(1.073 g/mL)分离的脐血间充质干细胞大小较为均匀，梭形或星形的成纤维细胞样细胞。细胞生长曲线测定表明接后第5天细胞进入指数增生期，至第9天后数量减少;流式细胞检测表明50%～70%细胞为CD29和CD45阳性。结论体外分离培养脐血间充质干细胞生长稳定，可作为组织工程的种子细胞。 【关键词】脐血;间充质干细胞;细胞周期;免疫细胞化学 Abstract: Objective Isolation and cultivation of mesenchymal stem cells (MSCs) in human umbilical cord in vitro, and determine their biological properties. Methods The mononuclear cells were isolated by density gradient centrifugation from human umbilical cord blood in sterile condition, and cultured in DMEM medium containing 10% fetal bovine serum. After the adherent mononuclear cells were obtained, the shape of cells were observed by microscope, then the cell growth curve, the cell cycle and the cell surface antigens were obtained by immunocytochemistry and flow cytometry methods. Results MSCs obtained by Percoll (1.073 g/mL) were similar in size, spindle-shaped or star-shaped fibroblasts-liked cells. Cell growth curve analysis indicated that MSCs were in the exponential stage after 5d and in the stationary stages after 9d. Flow cytometry analysis showed that the CD29 and CD44 positive cells were about 50%～70%. Conclusions The human umbilical cord derived mesenchymal stem cells were grown stably in vitro and can be used as the seed-cells in tissue engineering. Key words:human umbilical cord blood; mesenchymal stem cells; cell cycle; immunocytochemistry 间充质干细胞(mesenchymal stem cells，MSCs)在一定条件下具有多向分化的潜能，是组织工程研究中重要的种子细胞来源。寻找来源丰富并不受伦理学制约的间充质干细胞成为近年来的研究热点[1]。脐血(umbilical cord blood, UCB)在胚胎娩出后，与胎盘一起存在的医疗废物。与骨髓相比，UCB来源更丰富，取材方便，具有肿瘤和微生物污染机会少等优点。有人认为脐血中也存在间充质干细胞(Umbilical cord blood-derived mesenchymal stem cells，UCB-MSCs)。如果从脐血中培养出MSCs，与胚胎干细胞相比，应用和研究则不受伦理的制约，蕴藏着巨大的临床应用价值[2,3]。本研究将探讨人UCB-MSCs体外培养的方法、细胞的生长曲线、增殖周期和细胞表面标志等方面，分析UCB-MSCs 作为间充质干细胞来源的可行性。