手性固定相Chirex3001对安息香和联萘酚及其类似物的分子识别

利用分子力学方法,建立了苯基甘氨酸型手性固定相Chirex3001的简化模型,并探讨了手性固定相Chirex3001与安息香和联萘酚及其类似物的识别机制.模拟结果表明,固定相主体与手性客体分子识别作用的推动力主要来自于它们之间的π-π堆积、氢键和范德华等作用.主体与(S)-构型的客体1～3结合能力强于(R)-构型的客体,而对于客体4～6,则是与(R)-构型的结合强于(S)-构型,这与高效液相色谱拆分实验结果相符.客体1～3对映体在Chirex3001柱上的分离因子分别为1.02,1.04和1.11,(R)-构型先被洗脱;客体4～6对映体的分离因子分别为1.23,1.26和1.09,(S)-构型先被洗脱

丙氨酰谷氨酰胺二肽对人脐静脉内皮细胞ECV304缺氧缺糖损伤的保护作用

目的观察丙氨酰谷氨酰胺二肽(丙谷二肽)对人脐静脉内皮细胞ECV304缺氧缺糖损伤的保护作用,并探讨其可能的作用机制。方法在以低氧低糖培养人脐静脉内皮细胞ECV304为细胞损伤模型的基础上,以噻唑蓝(MTT)比色法优化丙谷二肽的最佳作用浓度,显微镜观察细胞形态变化,流式细胞术检测线粒体膜电位。自动生化分析仪测定乳酸脱氢酶(LDH)活性,比色法检测谷胱甘肽(GSH)、丙二醛(MDA)的浓度,RT-PCR方法检测细胞内肿瘤坏死因子-α(TNF-α)、白细胞介素-6(IL-6)、热休克蛋白70(HSP70)、葡萄糖调节蛋白78(GRP78)和缺氧诱导因子-1α(HIF-1α)mRNA的表达。结果丙谷二肽能够使细胞在缺氧缺糖应激下存活率增加,线粒体损伤减轻,LDH分泌降低,GSH产生增加,HSP70和HIF-1αmRNA的表达增加。结论丙谷二肽对细胞缺氧缺糖损伤有明显的保护作用,这种保护作用可能与保护线粒体、维持细胞膜结构完整、上调细胞中应激基因HSP70和HIF-1α的表达有关

Numerical simulation of immiscible two-phase flow in T-shaped microchannel

采用摄动有限体积(PFV)算法和水平集(level set)技术对T形微通道内互不相溶两相流动进行了数值模拟研究。考察了两相界面张力和微通道壁面润湿性对流动的影响,精确地捕捉到了油水两相流动的界面。对一些典型的T形微通道油水两相流动进行了数值计算,模拟结果和实验结果吻合较好。分析总结出了微通道内两相流动过程中的一些基本规律,为微通道内的液液两相流动实验设计和工业应用提供了新的数值预测手段

沙溪水污染对微生物群落变化的影响

沙溪是闽江上游3大支流之一.近年来,随着三明市经济的发展,局部污染事件仍时有发生.对沙溪三明河段的细菌、真菌、大肠菌群以及降解污染物的主要微生物进行了数量跟踪,结合COD、总氮和总磷等污染物对沙溪水环境与微生物群落变化的关系进行了初步的研究.结果表明:各种微生物的数量变化与主要的有机污染物值之间存在显著的相关性,所有的相关系数均大于0.7,表明微生物在降解与净化中起着重要的作用,同时对水环境的污染状况具有一定的指示作用;降解有机物的主要微生物的数量于COD显著相关,可作为该河段有机污染物水平的指标;研究结果还显示,三化总口和三农电化口是主要的有机污染点,应加强对这两个位点的监测和排污管理

用HPLC-MS-MS快速分析和鉴定三尖杉植物内生真菌发酵液中的Brefeldin A

采用HPLC -MS -MS联用技术 ,分析了C56和C65两株具有抗肿瘤活性的三尖杉植物内生真菌发酵液抽提物 ,首次报道了这两株真菌都能产生BrefeldinA(BFA)。采用ESI-MS总离子流跟踪分析HPLC的洗脱液 ,并用低能量的CID -MS -MS(碰撞诱导裂解方式 )进一步确定目标离子峰为BFA分子离子峰 ,这为植物内生真菌发酵液中的有效成分的早期鉴别奠定了基

Diatom diet selectivity by early post-larval abalone Haliotis diversicolor supertexta under hatchery conditions

Benthic diatoms constitute the primary diet of abalone during their early stages of development.To evaluate the dietary preferences of early post-larval abalone,Haliotis diversicolor supertexta,we analyzed the gut contents of post-larvae that settled on diatom films.We compared the abundance and species diversity of diatom assemblages in the gut to those of the epiphytic diatom assemblages on the attachment films,and identified 40 benthic diatom species in the gut contents of post-larvae 12 to 24 d after settlement.The most abundant taxa in the gut contents were Navicula spp.,Amphora copulate,and Amphora coffeaeformis.Navicula spp.accounted for 64.0% of the cell density.In the attachment films,we identified 110 diatom species belonging to 38 genera.Pennate diatoms were the dominant members including the species Amphiprora alata,Cocconeis placentula var.euglypta,Cylindrotheca closterium,Navicula sp.2,and A.coffeaeformis.Nano-diatoms(<20 μm in length) accounted for a considerable proportion of the total species..

Effects of mowing plus waterlogging on germination and seedling growth of Spartina alterniflora

互花米草(Spartina alterniflora)是我国危害最严重的外来入侵植物之一,探索环保、经济、有效地防治互花米草的技术对保护我国海滩生态环境具有重要意义。本研究通过人工气候室(20~25℃)的盆栽实验,研究刈割与淹水对互花米草萌发和幼苗生长的影响。实验持续4个月,对互花米草地上部分进行了2次刈割,首次刈割是在互花米草生长季结束时,3个月后进行第二次刈割。首次刈割后持续淹水至实验结束,淹水处理设计0、5、10、20 cm四个淹水深度。首次刈割后各淹水处理互花米草根茎上迅速萌发克隆苗,种子的萌发比克隆苗晚约3个月。不同淹水深度对克隆苗的萌发和生长均有抑制作用,克隆苗株数、株高和地上生物量均随淹水深度增加而减少。第二次刈割后各淹水处理均没有再萌发克隆苗,但有少量种子实生苗,其中20 cm水深处理的实生苗数量最少。刈割加淹水可以很好地抑制互花米草的萌发和幼苗生长,据此建议互花米草防治方案为:在春季萌芽前,修筑堤坝,保持淹水20 cm,在营养生长期后期贴地刈割互花米草,继续淹水,第二年重复同样的刈割和淹水。为防止二次入侵,需要在邻近的互花米草分布区同时进行治理。&nbsp;</p

Molecular recognition of benzoin and bi-beta-naphthol analogues by Chirex 3001-based chiral stationary phase

The simplified model of (R)-phenylglycine based chiral stationary phase (Chirex 3001) was built to investigate the process of chiral recognition of benzoin and bi-beta-naphthol and their analogues by molecular mechanics methods. The results showed that the driving force of chiral recognition came from the pi-pi stacking, hydrogen bond and van der Waals interactions between the host and the guest molecule. The host preferred to bind with S-enantiomers of benzoin and its analogues 1 similar to 3, and preferred to bind with R-enantiomers of bi-beta-naphthol and its analogues 4 similar to 6. This was consistent with the HPLC experimental results. The separation factors were 1.02, 1.04 and 1.11 respectively for compounds 1 similar to 3 when n-hexane/1,2-dichloroethane/ethanol (V : V : V=83.5 : 15 : 1.5) was used as mobile phase, and the R-enantiomers were eluted first. The separation factors were 1.23, 1.26 and 1.11 respectively when n-hexane/chloroform/ethanol (V : V : V=78.5 : 20 : 1.5) was used as mobile phase, and the S-enantiomers were eluted first

First Sagittarius A* Event Horizon Telescope Results. VIII. Physical Interpretation of the Polarized Ring

In a companion paper, we present the first spatially resolved polarized image of Sagittarius A* on event horizon scales, captured using the Event Horizon Telescope, a global very long baseline interferometric array operating at a wavelength of 1.3 mm. Here we interpret this image using both simple analytic models and numerical general relativistic magnetohydrodynamic (GRMHD) simulations. The large spatially resolved linear polarization fraction (24%–28%, peaking at ∼40%) is the most stringent constraint on parameter space, disfavoring models that are too Faraday depolarized. Similar to our studies of M87*, polarimetric constraints reinforce a preference for GRMHD models with dynamically important magnetic fields. Although the spiral morphology of the polarization pattern is known to constrain the spin and inclination angle, the time-variable rotation measure (RM) of Sgr A* (equivalent to ≈46° ± 12° rotation at 228 GHz) limits its present utility as a constraint. If we attribute the RM to internal Faraday rotation, then the motion of accreting material is inferred to be counterclockwise, contrary to inferences based on historical polarized flares, and no model satisfies all polarimetric and total intensity constraints. On the other hand, if we attribute the mean RM to an external Faraday screen, then the motion of accreting material is inferred to be clockwise, and one model passes all applied total intensity and polarimetric constraints: a model with strong magnetic fields, a spin parameter of 0.94, and an inclination of 150°. We discuss how future 345 GHz and dynamical imaging will mitigate our present uncertainties and provide additional constraints on the black hole and its accretion flow

STUDIES ON PURIFICATION OF PHTHALATE ACID ESTERS THROUGH INTEGRATED VERTICAL-FLOW CONSTRUCTED WETLAND

酞酸酯是目前世界上主要采用的增塑剂之一,也是中国使用最多的增塑剂.该论文应用复合垂直流构建湿地系统（IVCW）对水中酞酸酯类污染物的净化效果和机理进行了系统研究.主要进行了以下研究工作：1.将人工配制含DBP和DOP的污水流过温室中的IVCW小试系统,监测进出水中DBP和DOP含量的变化;又以DBP与DEHP（与DOP性质相似）二者同时投加到IVCW系统中以考察两种酞酸酯混合投加的净化效果;并且分别以两个成倍数关系的浓度投加到系统中以考察不同酞酸酯浓度下的净化效果.2.为考察IVCW系统中基质对酞酸酯的吸附作用,在实验期间对基质（表层0-5cm处）中的酞酸酯的浓度进行了检测.3.对IVCW系统的主要作用空间中的好氧微生物数量进行了测定,分析了不同酞酸酯对微生物的作用和不同流向池中微生物的特征.4.以DBP为例,研究了酞酸酯在太阳光下或紫外光下进行光解的可能性.5.为考察所投加的酞酸酯对IVCW系统中植物是否有影响,选取了叶绿素a/b和光化学效率以及生物量等指标,结合实地观察植株器官症状,将实验系统与对照系统相比较,衡量植物受危害的程度大小.说明酞酸酯的投加没有明显影响植物的生长.6.在稳定运行的IVCW中试系统中采集进出水和自来水水样,采用SPE-GC/MS方法对其中的痕量有机污染物进行了富集和测定.该研究工作首次利用IVCW系统对水环境中酞酸酯类污染物的净化效果及机理进行了研究和探讨,此外还首次考察了IVCW系统对于水体中其它痕量有机污染物的净化效果.该项研究成果为复合垂直流构建湿地系统净化污水中痕量有机污染物提供了重要的科学依据和工艺参数