Helical Shell Structures of Ni-A1 Alloy Nanowires and Their Electronic Transport Properties

Six kinds of Ni-A1 alloy nanowires are optimized by means of simulated annealing. The optimized structures show that the Ni-A1 alloy nanowires are helical shell structures that are wound by three atomic strands, which is very similar to the case with pure metallic nanowires. The densities of states （DOS）, transmission function T（ E）, current-voltage （I - V） curves, and the conductance spectra of these alloy nanowires are also investigated. Our results indicate that the conductance spectra depend on the geometric structure properties and the ingredients of the alloy nanowires. We observe and study the nonlinear contribution to the I-V characteristics that are due to the quantum size effect and the impurity effect. The addition of Ni atoms decreases the conductance of the Ni-A1 alloy nanowire because the doping atom Ni change the electronic band structures and the charge density distribution. The interesting statistical results shed light on the physics of quantum transport at the nano-scale.     

黄芩苷对惊厥持续状态幼年大鼠海马IL-lβ、NF-κB表达的影响

目的观察幼年大鼠惊厥持续状态（SC）后海马CA1区神经细胞凋亡以及IL-1β和NF-κB蛋白、MicroRNA表达变化,并了解黄芩苷（BC）对其影响。方法将195只19d龄SD雄性大鼠随机分成生理盐水对照组（NS组）、惊厥持续状态组（SC组）和黄芩苷预处理组（BC组）,每组65只;各组按处死时间点随机分为4、12、24、48和72h组。采用氯化锂-匹鲁卡品化学点燃法制备幼年大鼠SC模型;采用免疫组化法检测大鼠海马中IL-lβ、NF-κB蛋白表达,RT-PCR法检测NF-κBMicroRNA表达,TUNEL法检测神经细胞凋亡数。结果IL-lβ：与NS组（12、24、48和72h分别为11.47±2.51、12.49±2.58、13.19±2.39和12.79±5.30）比较,SC组（12、24、48和72h分别为29.38±5.18、40.09±5.16、35.32±6.59和27.98±4.16）表达增强（均P＜0.01）;与SC组比较,BC组（12、24和48h组分别为21.19±4.54、29.78±4.39和25.91±5.64）表达降低（均P＜0.05）。NF-κB：与NS组（4、12、24、48和72h组分别为45.76±15.41、41.26±6.28、50.61±12.54、51.72±6.52和52.65±7.65）比较,SC组（4、12、24、48和72h组分别为64.06±6.18、71.16±6.49、79.34±11.76、67.07±6.58和65.12±9.66）表达增强（均P＜0.05）;与SC组比较,BC组（4、12和24h组分别为52.65±5.73、56.68±5.37和67.01±9.08）表达降低（均P＜0.05）。NF-κBMicroRNA表达与蛋白表达相似。SC组在惊厥后12h海马CA1区神经细胞凋亡数为（11.38±2.35）个,高于NS组的（6.19±1.48）个（P＜0.01）,48h达到高峰（28.28±5.17）个;BC组在12、24、48和72h时神经细胞凋亡数分别为（8.96±2.21）、（13.07±2.47）、（20.51±4.39）和（17.36±4.12）个,均低于SC组（均P＜0.05）,但高于NS组（6.19±1.48）、（6.59±1.66）、（6.79±1.15）和（6.31±1.47）个（均P＜0.05）。结论幼年大鼠SC后海马CA1区IL-1β和NF-κB表达增强,神经细胞凋亡增加;BC预处理能抑制早期IL-1β和NF-κB蛋白、MicroRNA表达,减少神经细胞凋亡,对幼年鼠SC后脑损伤具有一定的保护作用。