简介：AbstractBackground:Delivery room resuscitation assists preterm infants, especially extremely preterm infants (EPI) and extremely low birth weight infants (ELBWI), in breathing support, while it potentially exerts a negative impact on the lungs and outcomes of preterm infants. This study aimed to assess delivery room resuscitation and discharge outcomes of EPI and ELBWI in China.Methods:The clinical data of EPI (gestational age [GA] <28 weeks) and ELBWI (birth weight [BW] <1000 g), admitted within 72 h of birth in 33 neonatal intensive care units from five provinces and cities in North China between 2017 and 2018, were analyzed. The primary outcomes were delivery room resuscitation and risk factors for delivery room intubation (DRI). The secondary outcomes were survival rates, incidence of bronchopulmonary dysplasia (BPD), and risk factors for BPD.Results:A cohort of 952 preterm infants were enrolled. The incidence of DRI, chest compressions, and administration of epinephrine was 55.9% (532/952), 12.5% (119/952), and 7.0% (67/952), respectively. Multivariate analysis revealed that the risk factors for DRI were GA <28 weeks (odds ratio [OR], 3.147; 95% confidence interval [CI], 2.082-4.755), BW <1000 g (OR, 2.240; 95% CI, 1.606-3.125), and antepartum infection (OR, 1.429; 95% CI, 1.044-1.956). The survival rate was 65.9% (627/952) and was dependent on GA. The rate of BPD was 29.3% (181/627). Multivariate analysis showed that the risk factors for BPD were male (OR, 1.603; 95% CI, 1.061-2.424), DRI (OR, 2.094; 95% CI, 1.328-3.303), respiratory distress syndrome exposed to ≥2 doses of pulmonary surfactants (PS; OR, 2.700; 95% CI, 1.679-4.343), and mechanical ventilation ≥7 days (OR, 4.358; 95% CI, 2.777-6.837). However, a larger BW (OR, 0.998; 95% CI, 0.996-0.999), antenatal steroid (OR, 0.577; 95% CI, 0.379-0.880), and PS use in the delivery room (OR, 0.273; 95% CI, 0.160-0.467) were preventive factors for BPD (all P < 0.05).Conclusion:Improving delivery room resuscitation and management of respiratory complications are imperative during early management of the health of EPI and ELBWI.

简介：AbstractPreterm parturition is the consequence of pathological signals that activate the common pathway of parturition and considered as a syndrome. Many risk factors for spontaneous preterm birth (sPTB) have been identified. Two significant risk factors for sPTB are history of prior sPTB and short cervical length at midtrimester. 17 hydroxyprogesterone caproate, vaginal progesterone, cerclage, and pessary have all been studied for prevention of sPTB. Difference in patient populations likely contributes to the conflicting study results. Further studies are needed to establish strategies in prevention of sPTB in singleton as well as multiple pregnancies.

简介：AbstractThe time of birth is a critical determinant of perinatal and long-term outcomes, and even trans-generational effects. Preterm birth is still the leading cause of infant mortality and morbidity. Unfortunately, rates of preterm birth remain high worldwide. Preterm parturition is a complex syndrome, which can be induced by several factors such as infection, cervical pathology, uterine overdistension, progesterone deficiency, vascular alterations (utero-placental ischemia, decidual hemorrhage), maternal and fetal stress, allograft reaction, allergic phenomena, and probably other several unknown factors. The mechanisms responsible for early labor activation have been partially identified and involve receptors, chemokines, and inflammatory cytokines. It is very useful to understand the cellular and biochemical pathways responsible for preterm labor activation to identify, treat, and prevent negative outcome in a timely manner. Researchers and clinicians play a key role in improving biochemical knowledge on preterm delivery, identifying risk factors, and applying multilevel preventive strategies.

简介：很多人认为法国人很臭、很懒、很粗鲁、拒绝说英语,但真相到底如何？

简介：AbstractPreterm labor (before 37 weeks’ gestation) is the leading cause of neonatal mortality and morbidity, which can be divided into iatrogenic preterm labor, infectious preterm labor, and spontaneous preterm labor (sPTL). Up to now, there continue to be great difficulties in prediction and prevention of sPTL, owing to multiple risk factors, pathogenesis, and pathologic processes contributing to the event, which have not been fully clarified. Pregnancy maintenance and parturition is a complicated process with continuous maternal-fetal dialogue, in which both maternal and fetal factors participate and affect the outcome of pregnancy, including sPTL. Besides, external factors can also participate in sPTL, individually or through the interaction with internal factors. In this article, we summarize recent studies regarding sPTL from our and other groups, and discuss the risk factors and pathogenesis of preterm birth from both external and internal (maternal and fetal) aspects, so as to provide theoretical evidences for the diagnosis, prevention, and treatment of sPTL in the future.

简介：OBJECTIVE:Ameta-analysisofpublishedrandomizedcontrolledtrialsinvestigatingthelongtermeffectofdexamethasoneonthenervoussystemofpreterminfants.DATASOURCES:OnlineliteratureretrievalwasconductedusingTheCochraneLibrary(fromJanuary1993toJune2013),EMBASE(fromJanuary1980toJune2013),MEDLINE(fromJanuary1963toJune2013),OVID(fromJanuary1993toJune2013),Springer(fromJanuary1994toJune2013)andChineseAcademicJournalFull-textDatabase(fromJanuary1994toJune2013).KeywordswerepreterminfantsanddexamethasoneinEnglishandChinese.STUDYSELECTION:Selectedstudieswererandomizedcontrolledtrialsassessingtheeffectofintravenousdexamethasoneinpreterminfants.Thequalityoftheincludedpaperswasevaluatedandthosewithoutthedevelopmentofthenervoussystemandanimalexperimentswereexcluded.QualityassessmentwasperformedthroughbiasriskevaluationinaccordancewithCochraneHandbook5.1.0softwareintheCochraneCollaboration.ThehomogeneousstudieswereanalyzedandcomparedusingRevman5.2.6software,andtheneffectmodelwasselectedandanalyzed.Thosepapersfailedtobeincludedinthemeta-analysisweresubjectedtodescriptiveanalysis.MAINOUTCOMEMEASURES:Nervoussysteminjuryinpreterminfants.RESULTS:Tenrandomizedcontrolledtrialswerescreened,involving1,038subjects.Amongthem512casesreceiveddexamethasonetreatmentwhile526casesservedasplacebocontrolgroupandblankcontrolgroup.Meta-analysisresultsshowedthattheincidenceofcerebralpalsy,visualimpairmentandhearinglossinpreterminfantsafterdexamethasonetreatmentwithin7daysafterbirthwassimilartothatinthecontrolgroup(RR=1.47,95%CI:0.97–2.21;RR=1.46,95%CI:0.97–2.20;RR=0.80,95%CI:0.54–1.18;P>0.05),butintelligencequotientwassignificantlydecreasedcomparedwiththecontrolgroup(MD=-3.55,95%CI:-6.59to-0.51;P=0.02).Preterminfantstreatedwithdexamethasone7daysafterbirthdemonstratedaninci

简介：AbstractPreterm birth (PTB) is defined as delivery before completing 37 weeks of gestation. It is the main cause of neonatal morbidity and mortality in the most countries. The inherent cervical length and strength are two main features of the cervix that determine whether or not a pregnant woman is at risk for PTB. Routine transvaginal cervical length screening was recommended for women with singleton pregnancy and history of prior spontaneous PTB, while the issue of universal cervical length screening and the screening in multiple gestations remain an object of debate. Strain sonoelastography and shear-wave sonoelastography have been used to evaluate the cervical stiffness in pregnant women, but the predictive value for PTB still requires further investigations. In this review, we will discuss the measurement methods of cervical length and cervical stiffness, and compare the value of cervical assessment by transvaginal ultrasound for predicting PTB in asymptomatic women.

简介：AbstractObjective:To evaluate the ability of cervical length (CL) at 28-32 weeks of gestation to predict spontaneous preterm delivery and preterm premature rupture of membranes (PPROM).Methods:It was a retrospective cohort study that vaginal ultrasonography at approximately 28-32 weeks of gestation was performed in 14,953 women between 17-49 years old with singleton pregnancies who delivered after 28 weeks of gestation at the Peking University First Hospital from June 2008 to December 2012. The pregnancy outcomes were followed and the relationship between the CL and preterm delivery or PPROM was assessed. The relative risk was calculated to assess group differences in the likelihood of an event occurring.Results:The overall prevalence of preterm delivery was 5.7% (858/14,953); the incidence for therapeutic preterm delivery was 2.1% (318/14,953), for spontaneous preterm delivery was 0.9% (133/14,953), and for PPROM was 2.7% (407/14,953). Excluding the 318 women who had therapeutic preterm delivery, the relative risk of preterm delivery for women with a CL between 25 mm and <30 mm, between 15 mm and <25 mm, and <15 mm was 3.7, 9.3, and 30.2, respectively. The sensitivity, specificity, and positive and negative predictive values of CL ≤25 mm at 28-32 weeks of gestation as the cut-off value for predicting preterm delivery were 19.8%, 97.5%, 23.4%, and 96.9%, respectively. For preterm delivery before 35 weeks of gestation, the sensitivity, specificity, and positive and negative predictive values of a CL ≤ 25 mm at 28-32 weeks of gestation as the cut-off value were 30.0%, 97.2%, 11.8%, and 99.1%, respectively. In addition, women with PPROM (n = 407) had significantly shorter CL (31.9 ± 7.4) mm at 28-32 weeks of gestation compared that of women without PPROM (34.0 ± 8.3) mm. The incidence of PPROM in women with a CL ≤25 mm at 28-32 weeks of gestation (19.4%, 79/407) was significantly lower than that for women with a CL >25 mm (80.6%, 328/407, P < 0.05).Conclusion:CL at 28-32 weeks of gestation can predict spontaneous preterm delivery, and is valuable for predicting PPROM.

简介：TheinfluencesofboththevolumeofPS/toluenesolutionintheUbbelohdeviscometerandtheprecisionofthetimemeasuringontheviscositybehaviorindiluteandextremelydiluteconcentrationregionareinvestigatedItwasfoundthattheinfluenceoftheformercanneglect,butthatofthelatterissoprominentthatthedatafluctuatebitterlyandlinearityofthecurveofthereducedviscosityvs.Concentration(ηsp/c～c)becomestoobadtoobeytheHugginsequationdowntotheextremelydiluteregion,despitetheerroroftheflowtimes△t≤0.2s,whichispermittedbytheconventionalmethodofviscositymeasurement.Throughstrictmathematicalanalyses,itwasfoundthatthcerror(E)ofthereducedviscosityisinproportionandinverseproportionto△tandconcentrationc,respectively.Sothelesstheconcentration,themoretheerroris.Consequently,alowestconcentrationlimitcLcorrespondingtogivenexperimentalerrormayexistanditwillbemeaninglessforfurtheroperationbelowcLbecauseofthegreatfluctuationofthedata.Therefore,itneedstoseriouslyreconsidertheapplicationoftheconventionalmethodofUbbelohdeviscositymeasurementintheextremelydilutepolymersolutionundertraditionalconditionsbecauseofthegreatinfluenceoftheexperimentalerror.

简介：Atheoreticalstudywasconductedtocharacterizehydraulicjumpoflaminarcircularliquidjets.Theobjectiveofthisresearchwastodeterminethejumplocationinasimpleexplicitform,Theeffectsofmanyfactorswereinvestigatedincludingnozzlediameter,jetexitpressure,nozzle-to-platespacing,jetvelocityandReynoldsnumber,ItwasfoundthatthetheoreticaldatacollapsedwellovertherangeofjetReynoldsnumber500≤Re≤1800withpreviousdata.

简介：Theself-assembledInAs/GaAsquantumdots(QDs)withextremelylowdensityof8×10~6cm~(-1)areachievedusinghighergrowthtemperatureandlowerInAscoveragebylow-pressuremetal-organicchemicalvapourdeposition(MOVCD).Asaresultofmicro-photoluminescence(micro-PL),forextremelylowdensityof8×10~6cm~(-1)InAsQDsinthemicro-PLmeasurementsat10K,onlyoneemissionpeakhasbeenachieved.ItisbelievedthattheInAsQDshaveagoodpotentialtorealizesinglephotonsources.

简介：Quantumeffectsplayanenhancementroleinp-pchainreactionsoccurringwithinstars.Suchanenhancementisquantifiedbyawavepenetrationfactorthatisproportionaltothedensityoftheparticipatingfuelparticles.Thisleadstoaninnovativetheoryfordenseplasma,anditsresultshowsgoodagreementwithindependentdataderivedfromthesolarenergyoutput.AnanalysisofthefirstZ-pinchmachineinmankind’shistoryexhibitingneutronemissionleadstoaderiveddeuteriumplasmabeamdensitygreaterthanthatofwater,withplasmavelocitiesexceeding10000km/s.Fusionpowercouldbeachievedbytheintersectionoffoursuchpinchedplasmabeamswithpowerfulhead-oncollisionsintheircommonfocalregionduetothebeamandtargetenhancedreaction.

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简介：KueishanTao(24°51'N,121°55′E)islocatedatatectonicjunctionofthefaultsystemextensionofTaiwanandthesouthernriftingendoftheOkinawaTrough.Aclusterofover30vents,atawaterdepthofabout10～20mofftheeasterntipofthetaoemitshydrothermalfluidsandvolcanicgasessuchasH2S.Asulfurchimneyormound,formedbycondensationofthesulfurcontainedinthehydrothermalfluid,canusuallybeseenaroundthevents.Thetallestchimneyreaches6m.Ventsdischargingayellowishfluidhavetemperaturesbetween92and116℃andflowratesashighas158t/h;ventsdischargingawhitishfluidhavelowertemperaturesofbetween48and62℃andlowerflowratesofabout7.0t/h.Theseworld-record,breakinglowpH(aslowas1.52)fluidsaretotallydifferentfromthosefoundintheblackandwhite-chimneysofthemid-oceanridges.MagnesiumandSiO2dataindicatethatthesehydrothermalfluidsprobablyoriginatefromadepthof915～1350mbelowthesurface.Whiletheratiosofmajorionsrelativetothesodiumofthesehydrothermalfluidsarequitesimilartoopenoceanwater,theratiosofSO4andchloridetosodiumseemtobehigherforsomeofthevents.ItissuggestedthatthevolcanicgasescontributeSO4andohlorinetothefluids,henceincreasingtheirratiosrelativetosodium.Somehydrothermalfluids,however,arefoundtobedepletedofthemajorelementswhichcanhavebeencausedbyphaseseparation.Theconcentrationsofironandmanganeseinthefluidsaremuchlowerthanthosefoundinthemid-oceanridges,whilethealuminiumcontentishigher.Fourspeciesofbenthos(Xenograpsustestudinatus,asnail,aseaanemone,andaSipuncala),1speciesofalgae(Corallinaceae),and1speciesoffish(Siganusfusescens)wererecordednearthehydrothermalvents.AmitoehondriaDNAsequencecomparisonofXenograpsustestudinatuswith6otherdecapodspeciesshowsthegreatestnumberofnitrogenbasedifferencesintheDNAfragmentsfrom225to270.Thegenediversit

简介：Low-frequencychorusemissionshaverecentlyattractedmuchattentionduetothesuggestionthattheymayplayimportantrolesinthedynamicsoftheVanAllenBelts.However,themechanism(s)generatingtheselow-frequencychorusemissionshavenotbeenwellunderstood.Inthisletter,wereportaninterestingcaseinwhichbackgroundplasmadensityloweredthelowercutofffrequencyofchorusemissionsfromabove0.1fce(typicalordinarychorus)to0.02fce(extremelylow-frequencychorus).Thoseextremelylow-frequencychoruswaveswereobservedinaratherdenseplasma,wherethenumberdensityNewasfoundtobeseveraltimeslargerthanhasbeenassociatedwithobservationsofordinarychoruswaves.Forsuprathermalelectronswhosefreeenergyissuppliedbyanisotropictemperatures,lineargrowthrates(calculatedusingin-situplasmaparametersmeasuredbytheVanAllenProbes)showthatwhistlermodeinstabilitycanoccuratfrequenciesbelow0.1fcewhenthebackgroundplasmadensityNeincreases.EspeciallywhenNereaches90cm^-3ormore,thelowestunstablefrequencycanextendto0.02fceorevenless,whichisconsistentwithsatelliteobservations.Therefore,ourresultsdemonstratethatadensebackgroundplasmacouldplayanessentialroleintheexcitationofextremelylowfrequencychoruswavesbycontrollingthewavegrowthrates.

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简介：AbstractBackground:Preterm premature rupture of membranes (PPROM) is associated with high neonatal morbidity and mortality. However, the influences of cesarean section (CS) on neonatal outcomes in preterm pregnancies complicated with PPROM are not well elucidated. The aim of this study was to investigate the influence of delivery modes on neonatal outcomes among pregnant women with PPROM.Methods:A retrospective cross-sectional study was conducted in 39 public hospitals in 14 cities in the mainland of China from January 1st, 2011 to December 31st, 2011. A total of 2756 singleton pregnancies complicated with PPROM were included. Adverse neonatal outcomes including early neonatal death, birth asphyxia, respiratory distress syndrome (RDS), pneumonia, infection, birth trauma, and 5-min/10-min Apgar scores were obtained from the hospital records. Binary variables and ordinal variables were respectively calculated by binary logistic regressions and ordinal regression. Numerical variables were compared by multiple linear regressions.Results:In total, 2756 newborns were involved in the analysis. Among them, 1166 newborns (42.31%) were delivered by CS and 1590 newborns belonged to vaginal delivery (VD) group. The CS proportion of PPROM obviously increased with the increase of gestational age (χ2 = 5.014, P = 0.025). Compared with CS group, VD was associated with a higher risk of total newborns mortality(odds ratio [OR], 2.38; 95% confidence interval [CI], 1.102–5.118; P = 0.027), and a lower level of pneumonia (OR, 0.32; 95% CI, 0.126–0.811; P = 0.016). However, after multivariable adjustment and stratification for gestational age, only pneumonia was significantly related with CS in 28 to 34 weeks group (OR, 0.34; 95% CI, 0.120–0.940; P = 0.038). There were no differences regarding to other adverse outcomes in the two groups, including neonatal mortality, birth asphyxia, Apgar scores, RDS, pneumonia, and sepsis.Conclusions:The proportion of CS of pregnant women with PPROM was very high in China. The mode of delivery does not affect neonatal outcomes of pregnancies complicated with PPROM.

简介：Adirectsynthesisofmethyllevulinatefromcellulosealcoholysisinmethanolmediumundermildcondition(180210C)catalyzedbyextremelylowconcentrationsulfuricacid(0.01mol/L)andtheproductisolationweredevelopedinthisstudy.Effectsofdifferentprocessvariablestowardsthecatalyticperformancewereperformedasafunctionofreactiontime.Theresultsindicatedthatsulfuricacidconcentration,temperatureandinitialcelluloseconcentrationhadsignificanteffectsonthesynthesisofmethyllevulinate.Anoptimizedyieldofaround50%wasachievedat210Cfor120minwithsulfuricacidconcentrationof0.01mol/Landinitialcelluloseconcentrationbelow100g/L.Theresultingproductmixturewasisolatedbyadistillationtechniquethatcombinesanatmosphericdistillationwithavacuumdistillationwheren-dodecanewasaddedtohelpdistilltheheavyfraction.Thelightfractionincludingmainlymethanolcouldbereusedasthereactionmediumwithoutanysubstantialchangeintheyieldofmethyllevulinate.ThechemicalcompositionandstructuraloflowerheavyfractionwerecharacterizedbyGC/MS,FTIR,1H-NMRand13C-NMRtechniques.Methyllevulinatewasfoundtobeamajoringredientoflowerheavyfractionwiththecontentover96%.Thispathwayisefficient,environmentallybenignandeconomicalfortheproductionofpurelevulinateestersfromcellulose.

简介：根据Anderson亲爱原则，为极其重的降雨(缩短的同样极端的降雨/降水)的预报的一个方法基于中国气象学的管理(CMA)的T213全球整体预言系统(EPS)的整体预报数据被开发。在20072010期间使用T213预报降水数据并且在20012010的JuneAugust的观察降雨数据，累积分发功能(CDF)的特征观察，T213EPS预报降水被分析。因此，根据在模型之间的CDF的连续差别，气候和EPS预报，极端降水预报索引(EPFI)的一个数学模型被建立并且适用在17312011年7月期间在中国预报几个极端降雨事件的实验。结果证明EPFI利用了模型的尾巴信息气候的CDF和极端降雨的提供的令人喜悦的的预报。EPFI为预先发给极端降雨的早警告37天基于T213EPS是有用的。与预报铅时间的扩展，EPFI变得不太熟练。结果也证明模型气候CDF的合理性具有到EPFI的技巧的重要重要性。

简介：AbstractObjective:To characterize and compare the microbiome signature in the maternal, intrauterine, and fetal environments and the associated bacterial species in women who experienced preterm birth and term birth.Methods:A total of 140 women with singleton pregnancies were enrolled in this study. Among them, 31 experienced spontaneous preterm delivery (gestational age < 37 weeks), and 28 of them experienced vaginal delivery at term. Maternal peripheral blood, saliva, and vaginal discharge samples and fetal membrane, amniotic fluid, and cord blood samples were collected immediately after delivery under sterile conditions. DNA was isolated from the fetal membrane and umbilical cord blood samples, and the V3-V4 region of the bacterial 16S rRNA gene was sequenced. The sequence data were quality-filtered, chimera-checked, and organized into operational taxonomic units (OTUs) based on phylogeny. Principal coordinate analysis of beta diversity measures was used for visualization. The linear discriminant analysis effect size (LEfSe) algorithm and Wilcoxon test were used to differentiate the microbiomes found in the fetal membranes and cord blood in the cases of preterm birth.Results:OTU analysis based on the 16S rRNA gene showed similar microbiomes in the maternal peripheral blood, amniotic fluid, fetal membranes, and cord blood. However, the LEfSe algorithm revealed significantly different bacterial compositions in the fetal environment between the preterm and term groups, with some of the bacterial species originating from the maternal peripheral blood or saliva.Conclusions:The bacteria in the intrauterine and fetal environments may originate from other body sites through hematogenous transmission, and may cause the occurrence of preterm birth.