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991.
992.
Szeto KC Lillerud KP Tilset M Bjørgen M Prestipino C Zecchina A Lamberti C Bordiga S 《The journal of physical chemistry. B》2006,110(43):21509-21520
A metal-organic framework (MOF) based on Pt, Y, and 2,2'-bipyridine-5,5'-dicarboxylate (BPDC), stable up to 400 degrees C, has been synthesized and characterized. In this MOF, the Pt centers are coordinated to Cl and the N atoms of the BPDC unit, giving a local environment similar to that found in a series of Pt-organic complexes with catalytic activity toward C-H bond cleavage of alkanes. This new material is a heterogeneous counterpart to the corresponding metal-organic complex. The structure, determined by single-crystal XRD data, is the repetition of three covalently bonded layers. These layers form a block, which is stacking as an (a)(b)(c) sequence along the crystallographic b-axis. Each layer contains the Pt-organic unit, while Y atoms represent the connection between adjacent layers. No covalent connection is present between layer (a) of a block and layer (c) of an adjacent block. EXAFS (BM29 at the ESRF) analysis supports the XRD data. As this MOF crystallizes under hydrothermal conditions, water acts both as solvent and as a direct ligand of Y. Accessibility to the metal centers is demonstrated by reversible water desorption/readsorption, as determined by TPA/TPD, FTIR, UV-vis, EXAFS, and XANES. Importantly, the results show that the as-synthesized material will not suffer a permanent loss in porosity upon solvent removal. In addition to water, methanol, ethanol, and acetonitrile can also access the internal void of the dehydrated phase. 相似文献
993.
994.
995.
Lin-Li Xu Xiu-Ju Zhang Lin-Hua Zhu Xiao-Nan Lian Kai Xu Ming-Cai Chen 《Journal of Macromolecular Science: Physics》2013,52(1):89-99
Pimelic acid (PA) was used to modify the surface of magnesium sulfate whiskers (M-HOS). The treated M-HOS and its effects as a function of concentration on the crystallization and morphology of isotactic polypropylene (iPP) were investigated. Scanning electron microscopy (SEM), wide-angle X-ray diffraction (WAXD), thermogravimetic analysis (TGA), and Fourier transform infrared spectroscopy (FTIR) revealed that PA reacted with M-HOS and formed magnesium pimelate on the surface after the reaction. The results of differential scanning calorimetry (DSC) and polarized light microscopy (PLM) showed that the treated M-HOS had the ability to induce β-spherulites, increase the crystallization temperature and decrease the size of spherulites in iPP. It was the most effective to form β-spherulites when the content of PA treated M-HOS was 5 wt%. 相似文献
996.
997.
将经硫辛酸修饰的铕纳米颗粒和蛋白质固定在石英玻璃表面或胶原蛋白隔离的石英玻璃表面,研究蛋白质对纳米铕岛膜荧光的增强作用.研究结果发现,在275nm激发波长下,铕纳米岛膜的荧光光谱与铕纳米颗粒溶液的荧光性质相似,且微量蛋白质的加入可以使铕纳米岛膜的荧光强度增强,但被石英玻璃片吸附后,铕纳米岛膜以及铕-蛋白质体系的荧光发射峰的位置由378.8nm红移至420nm,且胶原蛋白隔离铕纳米岛膜和滴加微量BSA蛋白质的荧光光谱相似,但荧光强度没有发生明显变化. 相似文献
998.
999.
Kai Xiong Yongping Zhu Lianshi Wang Tongmin Cai Anqiang Zhang Xiangbin Zeng 《Journal of Macromolecular Science: Physics》2013,52(7):1351-1369
Poly(ethene-co-1-butene)-graft-methyl methacrylate-acrylonitrile (PEB-g-MAN) was prepared by suspension grafting copolymerization of methyl methacrylate (MMA) and acrylonitrile(AN) onto PEB. PEB-g-MAN/SAN resin blends (ABMS) were prepared by blending PEB-g-MAN with styrene-acrylonitrile copolymer (SAN resin). The effects of AN/(MMA+AN) feed ratio (fAN), PEB/(PEB+MMA+AN) feed ratio (fPEB) and benzoyl peroxide (BPO) dosage on the monomer conversion ratio (CR), rubber's grafting ratio (GR), grafting efficiency (GE) of the copolymerization and the toughening effect of PEB-g-MAN on the SAN resin were investigated. FTIR quantitative analysis showed that when the weight percent of AN unit in the unextracted product was 21.5 wt% with fAN of 25 wt%, the toughening effect of unextracted PEB-g-MAN on SAN resin was the highest. Gel permeation chromatography (GPC) analysis showed that when fAN was 25 wt%, the grafted copolymer had the lowest molecular weight and ABMS had highest toughness. Transmission electron microscopy (TEM) analysis showed that the highest toughness occurred when the phase structure of ABMS was cocontinuous with fAN of 25 wt%. When fAN was 25 wt% PEB-g-MAN domains have numerous small SAN domains in them, which was occlusion structure. Scanning electron microscopy (SEM) analysis indicated that the ABMS fracture surfaces had plastic flow visible, which looked like a craze fibers morphology, for the sample with highest impact strength (fAN = 25 wt%). Dynamic mechanical thermal analysis (DMA) showed that the miscibility of the PEB phase and SAN phase improved after graft copolymerization of MMA and AN onto PEB. 相似文献
1000.
采用纳米沉淀法制备了半导体聚合物CN-PPV纳米粒子,并用改进的Stber方法对纳米粒子进行包覆,获得了发光稳定的SiO2/CN-PPV纳米粒子。用动态光散射(DLS)及透射电镜(TEM)方法对粒子尺寸进行了表征,结果表明包覆前的CN-PPV纳米粒子平均粒径约为30 nm,包覆获得SiO2/CN-PPV纳米粒子的平均粒径约为60 nm。通过紫外-可见吸收光谱及荧光光谱对包覆前后纳米粒子的发光性质进行了比较,发现共轭聚合物CN-PPV包覆后的发射光谱与包覆前相比发生了小的蓝移,表明共轭聚合物的分子构型可能发生了微小变化。SiO2包覆可以提高聚合物发光分子的光稳定性,并且提供用于生物分子耦联的表面,这类材料有望在生物医学成像中获得应用。 相似文献