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991.
Metallocenes are organometallic compounds with reversible redox profiles and tunable oxidation and reduction potentials, depending on the metal and substituents at the cyclopentadienyl rings. Metallocenes have been introduced in macromolecules to combine the redox‐activity with polymer properties. There are many examples of such hydrophobic polymer materials, but much fewer water‐soluble examples are found scattered across the polymer literature. However, in terms of drug delivery and other biological applications, water solubility is essential. For this very reason, all the synthetic routes to water‐soluble metallocene containing polymers are collected and discussed here. The focus is on neutral ferrocene‐ and ruthenocene‐containing and charged cobaltocenium‐containing macromolecules (i.e., symmetrical sandwich complexes). The synthetic protocols, self‐assembly behavior, and other benefits of the obtained materials are discussed.
992.
Fuzhou Wang Ryo Tanaka Zhengguo Cai Yuushou Nakayama Takeshi Shiono 《Macromolecular rapid communications》2016,37(16):1375-1381
α‐Diimine nickel complexes bearing bulky ortho‐sec‐phenethyl groups (bis{[N,N′‐(4‐methyl‐2,6‐di‐sec‐phenethylphenyl)imino]‐1,2‐dimethylethane}dibromonickel ( 1 ), bis{[N,N′‐(4,6‐dimethyl‐2‐sec‐phenethylphenyl)imino]‐1,2‐dimethylethane}dibromonickel ( 2 ), bis{[N,N′‐(4‐methyl‐2‐sec‐phenethylphenyl)imino]‐1,2‐dimethylethane}dibromonickel ( 3 )) and {bis[N,N′‐(2,4,6‐trimethylphenyl)imino]‐1,2‐dimethylethane}dibromidonickel ( 4 ) are used as a precatalyst for the polymerization of trans‐4‐octene upon activation with modified methylaluminoxane. These catalysts conduct chain‐walking polymerization of trans‐4‐octene to give polymers possessing propyl and butyl branches with high molecular weight and narrow molecular weight distribution. The branching structure depends on the nickel complex as well as the polymerization temperature, and the ratio of propyl branch was increased with increasing the bulkiness of the ligand and decreasing the polymerization temperature. Consequently, the most bulky 1 among the complexes used is found to polymerize trans‐4‐octene with high 1,5‐regioselectivity at −20 °C to give poly(1‐propylpentan‐1,5‐diyl).
993.
Yongfang Yang Lei Zhang Xiaotian Ji Lixin Zhang Hefang Wang Hanying Zhao 《Macromolecular rapid communications》2016,37(18):1520-1526
A facile and versatile method for the synthesis of Janus graphene oxide (GO) nanosheets with different structures is reported. Based on electrostatic assembly, Janus GO nanosheets can be easily functionalized with a template polymer or be defunctionalized by altering the ionic strength. By using this approach, Janus GO nanosheets are prepared successfully with hydrophobic polystyrene chains on one side and hydrophilic poly(2‐(dimethylamino)ethyl methacrylate) chains on the other side.
994.
A model for dependent default with hyperbolic attenuation effect and valuation of credit default swap 总被引:1,自引:0,他引:1
A hyperbolic function is introduced to reflect the attenuation effect of one firm's default to its partner.If two firms are competitors(copartners),the default inten- sity of one firm will decrease(increase)abruptly when the other firm defaults.As time goes on,the impact will decrease gradually until extinct.In this model,the joint distri- bution and marginal distributions of default times are derived by employing the change of measure,and the fair swap premium of a credit default swap(CDS)can be valued. 相似文献
995.
996.
自抗扰控制技术在捷联惯导动基座初始对准中的应用研究 总被引:1,自引:1,他引:1
提出并设计了应用自抗扰控制技术(ADRC)的捷联惯性系统动基座初始对准方案。通过数字仿真,将卡尔曼滤波与自抗扰控制的性能进行了详细的比较,证明该方法具有对准时间快,精度高,抗干扰能力强等特点。 相似文献
997.
We conducted dynamic and quasi-static compression experiments with low-density (ρ = 120 kg/m3) epoxy foam specimens. The specimens had a 10.0-mm-square cross-section and a length of 19.3 mm. Dynamic experiments were
conducted with a modified split Hopkinson pressure bar (SHPB), and the quasi-static experiments were conducted with a hydraulic
load frame device (MTS-810). In both cases, the specimens were loaded from one end at a constant velocity. Equally spaced
grid lines were marked on the specimens to monitor the deformation history. Digital images taken at equally spaced time intervals
gave the positions of each grid line. These images showed that a constant end-face velocity V produced a compaction wave front that traveled at a constant velocity C in both dynamic and quasi-static experiments. We described these results with a shockwave analysis that used a locking solid
material model. 相似文献
998.
镍钛记忆合金自补偿磨粒磨损性能研究 总被引:3,自引:3,他引:3
研究了高临界温度镍钛记忆合金一维自补偿磨粒磨损特性.结果表明,在一定温度下,镍钛记忆合金在摩擦过程中具有形状恢复能力,从而产生一维磨损自补偿作用.超弹状态镍钛记忆合金具有热弹性马氏体相变、高阻尼、应力感生马氏体、超弹性、高应变硬化指数和时效弥散析出强化等特性,这使得硬度较低的镍钛合金的耐磨性能远优于硬度较高的淬火45#钢.利用超弹状态镍钛记忆合金的磨损自补偿作用可望开发出新型抗磨形状记忆合金产品. 相似文献
999.
将层板横截面分为含裂纹区与不含裂纹区,在每一区内,根据夏变函数理论与特征函数展开法,得到了各自区内满足所有支配方程、裂纹表面边界条件与层间连续条件的位移与应力的特征展开式,然后利用分区广义变分原理满足裂纹表面边界以外的边界条件以及两区之间的交界条件,并由此求得奇异场控制量(广义应力强度因子)。 相似文献
1000.
A method for crack localization, based on so-called Local Modal Crack Sensitivity (LMCS), has recently been proposed by one of the Authors. As a major feature, the method only involves measuring eigenfrequencies. The method has already been used for beams of uniform cross section and homogeneous boundary conditions. In this paper, the method is extended to stepped beams, with both homogeneous and non-homogeneous boundary conditions. Experimental results confirm its usefulness for crack localization. Satisfactory localization of a second crack was also possible, so confirming the effectiveness of the method. 相似文献