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971.
The structural stabilities, bonding nature, electronic properties, and aromaticity of bare iridium trimers \(\rm{Ir}_3^{+/-}\) with different geometries and spin multiplicities are studied at the DFT/B3LYP level of theory. The ground state of the \(\rm{Ir}_3^{+}\) cation is found to be the 3A2 (C2v) triplet state and the ground state of the \(\rm{Ir}_3^{-}\) anion the 5A2 (C2v) quintet state. A detailed molecular orbital (MO) analysis indicates that the ground-state \(\rm{Ir}_3^{+}\) ion (C2v, 3A2) possesses double (σ and partial δ) aromaticity as well as the ground-state \(\rm{Ir}_3^{-}\) ion (C2v, 5A2). The multiple d-orbital aromaticity is responsible for the totally delocalized three-center metal-metal bond of the triangular Ir3 framework. \(\rm{Ir}_3^{-}\) (C2v, 1A1) structure motif is perfectly preserved in pyramidal Ir3M0/+ (Cs, 1A′) and bipyramidal \(\rm{Ir}_3M_2^{+/3+}\) (C2v, 1A1) (M = Li, Na, K and Be, Ca) bimetallic clusters which also possess the corresponding d-orbital aromatic characters. 相似文献
972.
研究了微波等离子体炬原子发射光谱(MPT-AES)法测定高温合金中非金属元素(As、B、P、Si)的分析方法,考察此方法对高温合金行业非金属检测需求的适应性。对镍基高温合金样品进行酸溶解处理,选择适用的微波等离子体炬分析谱线,进行检出限、精密度测定。4种非金属元素的检出限在0.03~0.12μg/mL,10次数据的相对标准偏差(RSD,n=10)为0.88%~1.9%,此方法可用于高温合金中非金属元素的测定。 相似文献
973.
A series of cellulose 3,5-dimethylphenylcarbamates(CDMPCs) with different degrees of substitution(DS) and degrees of polymerization(DP) were homogeneously synthesized in 1-allyl-3-methylimidazolium chloride(Amim Cl). Then, the CDMPCs were coated on silica gel and used as chiral stationary phases(CSPs), and their chiral recognition abilities for seven racemates were evaluated by high performance liquid chromatography. The results showed that DS and DP of CDMPCs had a great influence on chiral recognition abilities of the CSPs. The CSPs with the DS ≈ 1 gives a low chiral recognition to most racemates. On the contrast, the CSPs with the DS ? 2 exhibited high chiral separation abilities. For example, six racemates could be separated on the CSP with CDMPC of DS ≈ 2(CSP-2). Especially, for the enantioseparation of 1-(2-naphthyl) ethanol and Tr?ger's base, CSP-2 gave the highest separation ability in all of CSPs. On the other hand, when the DP of cellulose was in a range from 39 to 220, the chiral separation abilities of CDMPCs increased as the DP increased. This work demonstrates that the structure of cellulose esters such as DS and DP has important effect on their chiral separation ability, and therefore provides a practical method to design and prepare desirable CSPs for different racemates. 相似文献
974.
A new series of cellulose-graft-poly(N-isopropylacrylamide)(cellulose-g-PNIPAM) copolymers were prepared by atom transfer radical polymerization(ATRP) of N-isopropylacrylamide monomers from a cellulose-based macro-initiator, which was homogeneously synthesized in an ionic liquid 1-allyl-3-methylimidazolium chloride(Amim Cl). The composition of cellulose-g-PNIPAM copolymers could be adjusted by altering the feeding ratio and reaction time. The resultant copolymers with relatively high content of PNIPAM segments(molar substitution of PNIPAM ? 18.3) were soluble in water at room temperature. Aqueous solutions of cellulose-g-PNIPAM copolymers exhibited clear temperature-sensitive behavior, and their sol-to-gel phase transition properties were investigated by dynamic light scattering(DLS) and UV measurements. Compared with pure PNIPAM, the cellulose-g-PNIPAM copolymers possessed higher lower critical solution temperatures(LCST) in a range from 36.9 ?C to 40.8 ?C, which are close to normal human body temperature, and could be tuned by adjusting the content of PNIPAM segments in copolymers. Spherical structure of cellulose-g-PNIPAM copolymers formed at temperatures above LCST and its morphology was observed by TEM and SEM. These novel cellulose-g-PNIPAM copolymers may be attractive substrates for some biomedical applications, such as drug release and tissue engineering. 相似文献
975.
Jianxin Chen Dr. Chunyang Yu Dr. Zengqian Shi Songrui Yu Prof. Zhongyuan Lu Wengfeng Jiang Meng Zhang Prof. Wei He Prof. Yongfeng Zhou Prof. Deyue Yan 《Angewandte Chemie (International ed. in English)》2015,54(12):3621-3625
Well‐defined ultrathin nanotubes (30 nm in diameter and of micrometer‐scale length) were generated through the self‐assembly of a novel alternative copolymer synthesized using an epoxy–thiol click‐chemistry reaction. The self‐assembly mechanism was investigated both by experiments and using dissipative particle dynamics (DPD) simulations. The obtained nanotubes can be readily functionalized with carboxy groups, amino groups, peptides, or other groups by simple modular click copolymerization. 相似文献
976.
977.
采用ICP-AES检测H-ZF类玻璃中锑含量,对共存元素产生的光谱干扰进行校正,并运用离峰扣除背景消除玻璃基体钛铌的干扰。建立简单可靠的测试分析方法,回收率为95-110%,相对标准偏差≤2%,适合日常的快速分析的需要。 相似文献
978.
Zhengshen Hua Xin Zhang Xiaojing Feng Xiaoran Wang Jun He Xin Wang Huifen Peng 《中国化学快报》2019,30(3):792-796
Ti4+ ions were introduced to the VO43- substituted Li3Fe2(PO4)3 by sol-gel method. Simultaneous substitution of Ti4+ for Fe3+ and VO43- for PO43- in the Li3Fe2(PO4)3 resulted in a net improvement in the rate capability and cycling performance, as compared with the single Ti4+ or VO43- substituted compound. 相似文献
979.
近年来,钙钛矿太阳电池的光电转换效率取得了爆发式增长,这与电池中钙钛矿薄膜的制备工艺和材料组分密切相关.关于钙钛矿薄膜的制备方法,相关的研究报道及综述较多,然而钙钛矿材料组分调控方面的研究梳理工作相对缺乏.本综述总结了近年来不同组分体系钙钛矿材料的研究进展,包括有机无机铅卤钙钛矿、全无机铅卤钙钛矿、少铅钙钛矿以及无铅钙钛矿.重点介绍了不同体系中具有代表性的材料组分及其对器件性能的影响,旨在梳理通过组分调控提高钙钛矿电池的效率及稳定性的研究思路,最终实现商业化应用. 相似文献
980.