米花型银-氮化钛薄膜SERS基底的制备及罗丹明6G的检测研究

罗丹明6G的痕量检测需要具有较高的灵敏度,为提高SERS基底的增强因子从而提高检测灵敏度,设计了米花型SERS基底,采用有限元法对其拉曼增强效果进行仿真,模拟不同中心球半径r、米花花瓣轴a、b、c以及中心球与花瓣间距d条件下电场强度的变化,得出最佳结构参数,并计算其SERS增强因子。随后利用电化学沉积法制备该基底,并探究电压值以及柠檬酸三钠和AgNO_(3)的浓度配比对基底结构和性能的影响,从而制备出与理想物理模型形态最接近的米花型银/氮化钛薄膜基底。然后用其对罗丹明6G(R6G)进行痕量检测,探究该基底的拉曼增强效果以及稳定性。实验结果表明,当沉积电压为2V,柠檬酸三钠与AgNO_(3)浓度配比为1∶1 (2 mmol/L∶2 mmol/L)时,得到的米花型TiN-Ag复合SERS基底与理想化模型仿真形态最接近。经过计算得到该基底的增强因子可达10^(15),对罗丹明6G的检测限可达10^(-13)mol/L。实验结果证明设计的基底灵敏度高、稳定性强,可对食品非法添加剂的痕量检测提供技术支撑。

Analysis on Genetic Structure of Spartina alterniflora Populations in China Based on EH277045-derived Sequence

[Objective] This study aimed to analyze the genetic structure of eight populations of Spartina alterniflora in China at the nuclear DNA level.[Method] The EH277045-derived sequences were amplified from 75 samples in 8 populations and directly sequenced.Nucleotide diversity,haplotype diversity,the mean value of Nei＇s genetic distance,genetic differentiation index FST and other genetic parameters were calculated to estimate the genetic diversity and genetic differentiation of S.alterniflora populations in China.[Result] 75 samples were divided into 25 haplotypes by 28 polymorphic sites.Relatively high nucleotide diversity（π=0.011） and haplotype diversity（Hd=0.794） were detected.The mean value of Nei＇s genetic distance and genetic differentiation index FST among eight populations were 0.056 and 0.222,respectively,the Nei＇s genetic distance ranged from 0.000 to 0.189 and FST ranged from 0.000 to 0.444 between each pair of the eight populations.AMOVA result revealed that 79% and 21% of the total genetic variation was partitioned within and among S.alterniflora populations,respectively.[Conclusion] At the nuclear DNA level,there were a relatively high level of genetic diversity and a relatively low level of genetic differentiation among S.alterniflora populations in China,and the genetic diversity existed mainly within rather than among populations.