Joining experiments of CBN grains to AISI 1045 steel were conducted using Ag-Cu-Ti composite fillers containing TiX （X=B2 or N） particles at 920 ℃ for 5 min. The influences of TiB2 and TiN particles on the interfac...Joining experiments of CBN grains to AISI 1045 steel were conducted using Ag-Cu-Ti composite fillers containing TiX （X=B2 or N） particles at 920 ℃ for 5 min. The influences of TiB2 and TiN particles on the interfacial microstructure features between CBN and filler were investigated comparatively. The experimental results show that TiN particles are more effective than TiB2 ones to control the interfacial reaction and particularly the resultants. Thermodynamic analysis reveals that the varied interfacial reaction induced by the addition of TiB2 and TiN particles is mainly atttributed to the activity change of the B and Ti elements in the brazing reaction system.展开更多
A new glycoside, cervicoside, was isolated from the soft coral Sinularia cervicornis Tix Dur ., collected from the bay of Sanya, Hainan Island. Its chemical structure was determined by spectroscopic methods as hexadec...A new glycoside, cervicoside, was isolated from the soft coral Sinularia cervicornis Tix Dur ., collected from the bay of Sanya, Hainan Island. Its chemical structure was determined by spectroscopic methods as hexadecanyl 1 O β D arabinopyranosyloxy (1→4) [ β D arabinopyranosyloxy(1→4)] β D arabinopyranoside. Cervicoside(1) exhibited cytotoxicity against human SKMG 4, Hep G2 and CNE2 cell in vitro.展开更多
水系锌离子电池(ZIBs)以其低成本、高安全性和环境友好的优点受到了研究者的广泛关注,成为大规模电化学储能系统的理想选择之一。然而锌金属负极在应用时面临着锌枝晶生长、腐蚀反应和副反应等难以克服的障碍,严重制约了水系锌离子电池...水系锌离子电池(ZIBs)以其低成本、高安全性和环境友好的优点受到了研究者的广泛关注,成为大规模电化学储能系统的理想选择之一。然而锌金属负极在应用时面临着锌枝晶生长、腐蚀反应和副反应等难以克服的障碍,严重制约了水系锌离子电池的发展。探索可替代锌金属的储锌负极是应对上述问题的有效策略,因此研究者围绕过渡金属氧化物、硫化物和导电聚合物开展了深入研究。以TiX_(2)(X=S,Se)为代表的二维过渡金属硫族化合物(TMDs)具有较大的层间距和快速的离子传输通道,可作为锌离子电池的负极,但其储锌反应机制尚未得到完整的揭示。在本文中,我们使用密度泛函理论(DFT)计算方法系统地研究锌离子在TiX_(2)中的嵌入反应。首先我们采用群论去描述嵌锌TiX_(2)的稳定层间构型的特点,定义了一个依赖于超胞并且只涉及平移旋转两种对称操作的群,其子群可以用来描述层间构型的对称性,而且用来描述最稳定构型的子群总是倾向于有最大的阶数。基于该计算得到的一系列对应于不同放电深度的TiX_(2)的稳定结构,我们发现TiS_(2)和TiSe_(2)两种材料在锌嵌入/脱出过程中的开路电压(OCV)均低于0.5V。态密度(DOS)的计算结果表明TiX_(2)具有很好的电子导电性,而分波态密度(PDOS)的结果显示随着锌的嵌入闭壳层的Ti^(4+)还原成开壳层的Ti^(3+),并且伴随着Zn―X键的生成。Bader电荷分析的结果表明随着X的嵌入,X相比Ti得到了更多的负电荷,意味着X也参与了TiX_(2)的氧化还原过程。爬坡弹性带方法(CINEB)计算的结果证实了Zn^(2+)在TiX_(2)中具有较低的扩散能垒(对于TiS_(2)是0.333 e V,对于TiSe_(2)是0.338e V)。本文的研究结果不仅从本质上证明了TiX_(2)适合作为锌离子电池的嵌锌负极材料,而且为其他高性能TMDs电池材料的DFT研究提供了新的见解。展开更多
基金Funded by the National Fundamental Research Program of China (No.2009CB724403)Program for New Century Excellent Talents in University from Ministry of Education of China (No. NCET-07-0435)
文摘Joining experiments of CBN grains to AISI 1045 steel were conducted using Ag-Cu-Ti composite fillers containing TiX （X=B2 or N） particles at 920 ℃ for 5 min. The influences of TiB2 and TiN particles on the interfacial microstructure features between CBN and filler were investigated comparatively. The experimental results show that TiN particles are more effective than TiB2 ones to control the interfacial reaction and particularly the resultants. Thermodynamic analysis reveals that the varied interfacial reaction induced by the addition of TiB2 and TiN particles is mainly atttributed to the activity change of the B and Ti elements in the brazing reaction system.
文摘A new glycoside, cervicoside, was isolated from the soft coral Sinularia cervicornis Tix Dur ., collected from the bay of Sanya, Hainan Island. Its chemical structure was determined by spectroscopic methods as hexadecanyl 1 O β D arabinopyranosyloxy (1→4) [ β D arabinopyranosyloxy(1→4)] β D arabinopyranoside. Cervicoside(1) exhibited cytotoxicity against human SKMG 4, Hep G2 and CNE2 cell in vitro.
文摘水系锌离子电池(ZIBs)以其低成本、高安全性和环境友好的优点受到了研究者的广泛关注,成为大规模电化学储能系统的理想选择之一。然而锌金属负极在应用时面临着锌枝晶生长、腐蚀反应和副反应等难以克服的障碍,严重制约了水系锌离子电池的发展。探索可替代锌金属的储锌负极是应对上述问题的有效策略,因此研究者围绕过渡金属氧化物、硫化物和导电聚合物开展了深入研究。以TiX_(2)(X=S,Se)为代表的二维过渡金属硫族化合物(TMDs)具有较大的层间距和快速的离子传输通道,可作为锌离子电池的负极,但其储锌反应机制尚未得到完整的揭示。在本文中,我们使用密度泛函理论(DFT)计算方法系统地研究锌离子在TiX_(2)中的嵌入反应。首先我们采用群论去描述嵌锌TiX_(2)的稳定层间构型的特点,定义了一个依赖于超胞并且只涉及平移旋转两种对称操作的群,其子群可以用来描述层间构型的对称性,而且用来描述最稳定构型的子群总是倾向于有最大的阶数。基于该计算得到的一系列对应于不同放电深度的TiX_(2)的稳定结构,我们发现TiS_(2)和TiSe_(2)两种材料在锌嵌入/脱出过程中的开路电压(OCV)均低于0.5V。态密度(DOS)的计算结果表明TiX_(2)具有很好的电子导电性,而分波态密度(PDOS)的结果显示随着锌的嵌入闭壳层的Ti^(4+)还原成开壳层的Ti^(3+),并且伴随着Zn―X键的生成。Bader电荷分析的结果表明随着X的嵌入,X相比Ti得到了更多的负电荷,意味着X也参与了TiX_(2)的氧化还原过程。爬坡弹性带方法(CINEB)计算的结果证实了Zn^(2+)在TiX_(2)中具有较低的扩散能垒(对于TiS_(2)是0.333 e V,对于TiSe_(2)是0.338e V)。本文的研究结果不仅从本质上证明了TiX_(2)适合作为锌离子电池的嵌锌负极材料,而且为其他高性能TMDs电池材料的DFT研究提供了新的见解。
