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41.
A simple one-step synthesis of 2,6-dimethylanthracene, 1, in high yield is reported utilizing the easily accessible benzyl alcohol as the starting material. Based on 2,6-dimethylanthracene, two pseudo-triptycene compounds, cis-2,6-dimethyl-9,10-dihydroanthracene-9,10-endo-α,β-succinic anhydride, 2, and cis-2,6-dimethyl-9,10-dihydroanthracene-9,10-endo-α,β-succinyl amine, 3, are firstly synthesized in high yield and they are characterized by single crystal X-ray diffraction. Compound 2 crystallizes in triclinic space group and compound 3 crystallizes in monoclinic P21/c space group. Both compound 2 and 3 exhibit cis-configurations and endo-conformations. Compound 1 exhibits very intense photoluminescence property due to the delocalized electron in the whole molecule, whereas fluorescence quench happens to some extents due to the destruction of the conjugated structure in compound 2. 相似文献
42.
A metal bellows-based fiber Bragg grating(FBG) accelerometer is proposed and experimentally demonstrated. The optical fiber(containing the FBG) is pre-tensioned,and the two ends of the optical fiber are fixed directly from the shell to the inertial mass. In this design,the FBG is uniformly tensioned to obtain a constant strain distribution over it. By employing this configuration,the FBG always has a sharp reflection characteristic with no broadening in its reflection spectrum during wavelength shifting. Dy... 相似文献
43.
TiO2 nanowires were grown on titanium foil by an alkali hydrothermal growth method. The as-synthesized nanowires are structurally uniform with diameters of 50-100 nm and lengths of up to a few micrometers. The as-prepared TiO2 nanowires were coated with Ag nanoparticles by reducing AgNO3 in solution. The experimental results indicate that the Ag nanoparticles can aggregate together on the surfaces of TiO2 nanowires by interconnection between nanoparticles. The degree of aggregation of Ag nanostructures can be controlled by changing the concentrations of Ag nanoparticles. The as-prepared nanostructures exhibit a wide optical absorption from 387 to 580 nm that can be easily tuned by controlling the degree of aggregation of Ag nanostructures. The results reveal that optical properties of the Ag-coated TiO2 nanowires can be enhanced by plasmon coupling of Ag nanoparticles. The as-prepared nanostructures may find potential applications in the field of solar cells. 相似文献
44.
45.
Ying Gao Honglian Huang Zhanhai Yao Dean Shi Zhuo Ke Jinghua Yin 《Journal of Polymer Science.Polymer Physics》2003,41(15):1837-1849
Blends of linear low‐density polyethylene (LLDPE) with polystyrene (PS) and blends of LLDPE with high‐impact polystyrene (HIPS) were prepared through a reactive extrusion method. For increased compatibility of the two blending components, a Lewis acid catalyst, aluminum chloride (AlCl3), was adopted to initiate the Friedel–Crafts alkylation reaction between the blending components. Spectra data from Raman spectra of the LLDPE/PS/AlCl3 blends extracted with tetrahydrofuran verified that LLDPE segments were grafted to the para position of the benzene rings of PS, and this confirmed the graft structure of the Friedel–Crafts reaction between the polyolefin and PS. Because the in situ generated LLDPE‐g‐PS and LLDPE‐g‐HIPS copolymers acted as compatibilizers in the relative blending systems, the mechanical properties of the LLDPE/PS and LLDPE/HIPS blending systems were greatly improved. For example, after compatibilization, the Izod impact strength of an LLDPE/PS blend (80/20 w/w) was increased from 88.5 to 401.6 J/m, and its elongation at break increased from 370 to 790%. For an LLDPE/HIPS (60/40 w/w) blend, its Charpy impact strength was increased from 284.2 to 495.8 kJ/m2. Scanning electron microscopy micrographs showed that the size of the domains decreased from 4–5 to less than 1 μm, depending on the content of added AlCl3. The crystallization behavior of the LLDPE/PS blend was investigated with differential scanning calorimetry. Fractionated crystallization phenomena were noticed because of the reduction in the size of the LLDPE droplets. The melt‐flow rate of the blending system depended on the competition of the grafting reaction of LLDPE with PS and the degradation of the blending components. The degradation of PS only happened during the alkylation reaction between LLDPE and PS. Gel permeation chromatography showed that the alkylation reaction increased the molecular weight of the blend polymer. The low molecular weight part disappeared with reactive blending. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 1837–1849, 2003 相似文献
46.
Coherent synthesis using carrier-envelope phase-controlled pulses from a dual-color femtosecond optical parametric oscillator 总被引:3,自引:0,他引:3
By using a dual-color femtosecond optical parametric oscillator (OPO), a coherent waveform was synthesized from two coresonant near-infrared signal pulses whose center wavelengths had a separation of 100 nm. Immediately after the OPO cavity the pulses had independent carrier-envelope phase-slip frequencies, and synthesis was achieved by shifting these frequencies using an acousto-optic modulator driven by an internally generated difference frequency. Soliton self-frequency shifted pulses from a photonic crystal fiber and a cross-correlation frequency-resolved optical gating (XFROG) measurement were used to analyze the result of the synthesis experiment and revealed that the synthesized waveform was a train of high-contrast 30 fs pulses. 相似文献
47.
48.
Fang Liu Wenping Deng Yan Zhang Shenguang Ge Jinghua Yu Mei Yan 《Mikrochimica acta》2014,181(1-2):213-222
We report on a disposable microdevice suitable for sandwich-type electrochemiluminescence (ECL) detection of DNA. The method is making use of CdTe quantum dots functionalized with hierarchical nanoporous PtFe (CdTe@PtFe) nanoparticles and with magnetic graphene nanosheets. The latter were selected as carriers for the capture DNA due to their excellent biomagnetic separation capability and electrical properties. The CdTe@PtFe nanoparticles were used to label the signal DNA which resulted in distinctly enhanced ECL owing to the large specific surface area and good electrical conductivity of the PtFe alloy. A DNA sensor was constructed on a disk-shaped indium tin oxide electrode that was fabricated via etching. Under optimal conditions, the biosensor responds linearly to DNA in the 0.02 fM to 5000 fM concentration range, with a detection limit as low as 15 aM. The electrode is regenerable. The method displays excellent specificity, extremely good sensitivity, and is highly reproducible. Figure
CdTe quantum dots functionalized hierarchical nanoporous PtFe alloy (CdTe@PtFe) and magnetic graphene nanosheet (MGN) were applied for sensitive sandwich-type electrochemiluminescence DNA detection based on a disposable microdevice. The method displays excellent specificity, extremely good sensitivity, and is highly reproducible. 相似文献
49.
Tsuchiya T Imai H Miyoshi S Glans PA Guo J Yamaguchi S 《Physical chemistry chemical physics : PCCP》2011,13(38):17013-17018
The electronic structure and modification of the local interatomic structure of a reactive sputtered amorphous tantalum oxide (a-TaO(x)) thin film with the variation of oxygen nonstoichiometry, x in a-TaO(x) have been investigated by X-ray absorption spectroscopy (XAS), X-ray photoemission spectroscopy (XPS), Raman scattering spectroscopy, and Rutherford back scattering spectroscopy. A parallel chemical shift of Ta4f(7/2) and O1s core levels observed with the variation of x indicates the Fermi level shift by reduction and oxidation in the framework of the rigid band model. Extended X-ray absorption fine structure (EXAFS) suggests both the increase of average coordination number of the first Ta-O shell in polyhedra and a considerable reduction of the average Ta-O bond length with the increase of x. The relative intensity of Raman shift peaks at 670 cm(-1) and 815 cm(-1), corresponding to Ta-O stretching of TaO(6) octahedra and TaO(5) probably with a pyramidal form, respectively, drastically changes between x = 2.47 to 1.86, suggesting the change in the predominant polyhedron from TaO(6) to TaO(5) with a modification in multiplicity of oxygen by the reorganization of the polyhedral network. 相似文献
50.
A tunable multi-function broadband splitter consisted of a silver film, Kerr medium and a silver grating sandwiched between linear dielectrics waveguides is proposed and numerically investigated. This splitter can realize the functions of the beam splitter, the polarization splitter and wavelength beam splitter. This surface plasmon based device provides a unique approach for polarization sensitive manipulation of light in an integrated circuit and will be essential for future classical and quantum information processes. 相似文献