Ce4+对东北红豆杉细胞有丝分裂的影响

以悬浮培养的东北红豆杉细胞为材料,研究了不同浓度的Ce4 在不同处理时间对细胞有丝分裂的影响。结果显示,Ce4 能诱发东北红豆杉细胞多种异常有丝分裂,在浓度为0.5mmol/L、处理时间为5h时,即开始出现异常有丝分裂现象,而且细胞有丝分裂指数(MI)比对照组明显降低(P<0.05),表明细胞有丝分裂受到抑制,Ce4 对细胞有丝分裂过程有显著影响。Ce4 具有一定遗传毒性。     

小麦幼苗根系在Cr6+胁迫下生长和DNA含量的变化

[目的]研究重金属Cr<'6+>对小麦幼苗根系生长和DNA含量的影响.[方法]用浓度5～100 mg/L Cr<'6+>分别处理3和10 d龄小麦幼苗,测定生长指标,采用紫外分光光度法和电泳法测定DNA含量变化.[结果]除了Cr<'6+>>20 mg/L时,3d龄幼苗的根数小于对照根数外,其余处理根数均增加;而根长、根系鲜重和干重、DNA含量均随着Cr<'6+>浓度的增加而降低.3d龄幼苗比10 d龄幼苗对Cr<'6+>更敏感.琼脂糖凝胶电泳显示,对照根尖DNA带基本完整,而Cr<'6+>处理的DNA则发生了降解,出现拖尾现象.[结论]Cr<'6+>处理影响了小麦幼苗根系的正常生长并导致DNA含量下降.     

粘结剂含量对粘结NdFeB磁体磁性能和抗压强度的影响

用环氧树脂粘结剂制备了NdFeB粘结磁体,探讨了粘结剂含量对粘结磁体磁性能和抗压强度的影响规律及机理.当粘结剂含量为1%(质量分数,下同)时,磁粉不能完全被包覆、粘结,磁体密度、磁性能和抗压强度低;当粘结剂含量为5%时,粘结剂体积分数大,稀释了磁体的磁性能,多余的粘结剂也使磁体抗压强度降低.粘结剂含量为2.5%时磁体具有较佳的性能:剩磁Br=0.616T;内禀矫顽力Hcj=784kA/m;最大磁能积(BH)m=58kJ/m3;抗压强度为236MPa.     

Si含量对超超临界汽轮机转子钢30Cr2Ni4MoV组织和性能的影响

30Cr2Ni4MoV钢(%:0.15～0.16C、0.03～0.45Si、0.12～0.14Mn、0.005P、0.005～0.006S、1.62～1.72Cr、3.60～3.63Ni、0.52～0.53Mo、0.07V、≤0.005A1)由10kg真空感应炉冶炼,锻后经930℃空冷+900℃空冷+640℃空冷处理,再经850℃水淬+600℃回火调质处理。试验结果表明,当钢中的Si含量由0.03%增加至0.45%时,钢中马氏体量增加,晶粒更为粗大;钢的抗拉和屈服强度分别从922～936 MPa和868～873 MPa增至1015～1028 MPa和950～959 MPa,但平均冲击功由205 J降至154 J。     

Dynamic Effects of Cerium on Syntheses of Soluble Protein and Taxol in Suspension Culture of Taxus Chinensis Var. Mairei Cells

ＣｅｌｌｃｕｌｔｕｒｅｏｆＴａｘｕｓｓｐｐ .ｍａｙｂｅｖｉｅｗｅｄａｓａｐｏｔｅｎｔｉａｌａｌｔｅｒｎａｔｉｖｅｔｏｗｈｏｌｅｐｌａｎｔｅｘｔｒａｃ ｔｉｏｎａｓａｓｏｕｒｃｅｏｆｔｈｅａｎｔｉｎｅｏｐｌａｓｔｉｃａｇｅｎｔｔａｘ ｏｌａｎｄｒｅｌａｔｅｄｔａｘａｎｅｓ ,ｃｕｒｒｅｎｔｌｙｉｎｓｈｏｒｔｓｕｐ ｐｌｙ .Ｔｈｅｒｅｆｏｒｅ ,ｈｏｗｔｏｉｎｃｒｅａｓｅｔｈｅｐｒｏｄｕｃｔｉｖｉ ｔｙｏｆｔａｘｏｌｉｎｔｈｅｐｌａｎｔｃｅｌｌｃｕｌｔｕｒｅｈａｓｄｒａｗｎｍｕｃｈａｔｔｅｎｔｉｏｎ .Ｅｌｉ…     

稀土元素铈对红豆杉细胞膜透性的影响

用EvansBlue染色、细胞培养液电导率测定、MDA含量检测、电镜技术研究Ce4 对悬浮培养的东北红豆杉细胞膜的影响。结果表明:1mmol/LCe4 诱导后第5天,EvansBlue染色结果、细胞培养液的电导率、MDA含量显著地增加,细胞膜透性明显增大,细胞膜的完整性也受到一定程度的破坏,透射电镜观察细胞超微结构发生变化,说明1mmol/LCe4 能导致悬浮培养的红豆杉细胞膜的损伤。     

Ce4＋-Induced Apoptosis of Taxus cuspidata Cells in Suspension Culture

The standard detection hallmarks of apoptosis of Taxus cuspidata cells in suspension culture with Ce4 were studied. The condensation and margination of chromatin were observed under the electron microscopy. DNA fragmentation ranged “DNA ladder“ on agarose gel electrophoresis. TdT-mediated dUTP nick end labeling (TUNEL) analysis of the cells reveals that the nuclear DNA strand breaks can be identified by labeling free 3‘-OH termini. These results suggest that Ce4 can induce apoptosis of Taxus cuspidata cells and also indicate that there is a certain relationship between apoptosis and secondary metabolite preduct-Taxol.     

硝酸铈对红豆杉细胞培养及紫杉醇合成的影响

本文采用电子显微镜及聚丙烯酰胺凝胶电泳等方法 ,研究了稀土对红豆杉细胞培养中生物量积累及紫杉醇合成与释放的影响 ,同时进一步探讨了稀土调控次生代谢的机制。结果表明 ,适量稀土可促进紫杉醇合成 ,并对细胞的酶系统及超微结构产生一定影响。     

Ab Initio Calculation of 4f→5d Transition Energy and Electronic Structure of Ce3+ Doped in LiYF4 Crystal

The electronic structures of LiYF4:Ce3 and LiYF4 crystals simulated by an embedded (in a microcrystal containing 1938 ions) cluster CeY4Li8F24, and Y5Li8F24 respectively, were computed by the ab initio self-consistent relativistic DV-Xa(discrete variational Xa) method. The ground-state calculation showed that only the lowest 5d level Ed of Ce3 ion lies around the BCB (bottom of the conduction band) while the lowest 4f levels is 2.5 eV lower than BCB. The CB states consist of 4p of Y mixed with 5d of Ce, even for the wavefunctions (WFS) of Ed under BCB there are still 24% of Y-4p and 9% of F-2p as components. Furthermore, transition state (TS) calculation was performed in this work to obtain the 4f→5d transition energies Efd, to improve the calculation of Ref.[6] in which a small CeF8 cluster embedded in an array of point charge was used and the results of ground-state calculation were roughly used to compare directly with the observed 4f→5d transition energies. The ionic radius of Ce3 is larger than that of Y3 , for modeling approximately the lattice relaxation, we simply let the eight fluorine ions of the nearest-neighbor and next-nearest-neighbor move out radially and simultaneously. As results, the CeY4Li8F24 cluster with 4.56% outward relaxation of the eight fluorines has the lowest total energy and gave satisfactory 4f→5d energies Efd, but the calculated ground-state Ed is 0.68 eV higher than BCB. For another cluster with 7.36% outward relaxation the Ed is 0.43 eV lower than BCB, which makes the observation of fine structure (including zero-phonon line) of the lowest 5d band understandable easier, but the splits between the transition energies Efd were not as good as the former. Therefore, we consider the relaxation is somehow around 4.56%～7.36% outward, not as large as 10%.     

Effects of Ce^3＋ on improvement of spectral characteristics and function of chloroplasts damaged by linolenic acid in spinach

Linolenic acid has great effects on the structure and function of chloroplast. We studied the effects of Ce3+ on the improvement of chloroplast spectral characteristics and oxygen evolution damaged by linolenic acid in spinach. Results showed that Ce3+ could decrease the light absorption increased by linolenic acid and promote the distribution of excitation energy to PS Ⅱ and alleviate the decrease of PS Ⅱ fluo-rescence yield caused by linolenic acid. The linolenic acid treatments in various concentrations reduced the oxygen-evolving rate of chloro-plasts, but the rate was accelerated since adding Ce3+.