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Zhou L.,Nanjing University | Zhou L.,Nanjing Xiaozhuang University | Yu X.,Nanjing Southeast University | Zhu J.,Nanjing University
Nano Letters | Year: 2014

Nanostructure-based photovoltaic devices have exhibited several advantages, such as reduced reflection, extraordinary light trapping, and so forth. In particular, semiconductor nanostructures provide optical modes that have strong dependence on the size and geometry. Metallic nanostructures also attract a lot of attention because of the appealing plasmonic effect on the near-field enhancement. In this study, we propose a novel design, the metal-core/ semiconductor-shell nanocones with the core radius varying in a linearly gradient style. With a thin layer of semiconductor absorber coated on a metallic cone, such a design can lead to significant and broadband absorption enhancement across the entire visible and near-infrared solar spectrum. As an example of demonstration, a layer of 16 nm thick crystalline silicon (c-Si) coated on a silver nanocone can absorb 27% of standard solar radiation across a broad spectral range of 300-1100 nm, which is equivalent to a 700 nm thick flat c-Si film. Therefore, the absorption enhancement factor approaching the Yablonovitch limit is achieved with this design. The significant absorption enhancement can be ascribed to three types of optical modes, that is, Fabry-Perot modes, plasmonic modes, and hybrid modes that combine the features of the previous two. In addition, the unique nanocone geometry enables the linearly gradient radius of the semiconductor shell, which can support multiple optical resonances, critical for the broadband absorption. Our design may find general usage as elements for the low cost, high efficiency solar conversion and water-splitting devices. © 2014 American Chemical Society.

Lang L.,Nanjing University | Lang L.,Nanjing Xiaozhuang University | Xu Z.,Nanjing University
ACS Applied Materials and Interfaces | Year: 2013

The porous Fe3O4/C microbelts (FCBs) were synthesized by simple electrospinning method, combined with carbonization of the precursor microbelts at high temperature in N2 flow. Compared with α-Fe2O3 microbelt, the FCBs show better cyclic performance. The high capacity of 710 mA h g-1 is still maintained after 50 cycles. The excellent performance of FCBs in lithium-ion batteries can be attributed to the highly stable porous belt structure of FCBs and to the substantial structure carbon matrix surrounded Fe3O4 nanoparticles. The synthesis method is simple, cheap, and green and could be extended to fabricate other carbon composites. © 2013 American Chemical Society.

Wang X.,Nanjing University | Zhang C.,Nanjing Xiaozhuang University | Jiao Y.,Nanjing University | Guo Z.,Nanjing University
Chemical Science | Year: 2012

Alzheimer's disease (AD) is a neurodegenerative illness associated with amyloid β-peptide (Aβ) aggregation in the brain. Aβ shows high affinity for metal ions such as Zn 2+ and Cu 2+, which constitutes the major reason for the Aβ aggregation and related neurotoxicity. Metal chelators are potential therapeutic agents for AD because they could sequester metal ions from the Aβ aggregates and reverse the aggregation. In this study, two macrocyclic platiniferous chelators (PC1, PC2) with cyclen as the metal-chelating unit and Pt(bipyridine)Cl 2 as the Aβ-binding unit have been designed as novel bifunctional inhibitors of the metal-induced Aβ aggregation. The interactions between the chelators and Aβ40 aggregates are studied by tandem mass spectrometry and 1H NMR. The platinum centers in PC1 and PC2 are shown to coordinate with histidine residues (His-14 or -13) of Aβ40. The inhibitory effect of the chelators on Aβ40 aggregation induced by Zn 2+ and Cu 2+ ions is investigated using turbidimetry, a BCA protein assay, and transmission electron microscopy. PC1 and PC2 show significant inhibition against the Aβ aggregation and the action is more effective than that exerted by cyclen. By contrast, the corresponding anticancer drug cisplatin exhibits no inhibition against the Aβ aggregation. PC1 and PC2 can also suppress the Cu-Aβ40 mediated generation of reactive oxygen species and their corresponding neurotoxicity in cortical neuronal cells of mice, and reduce the extent of Aβ aggregation in the brain homogenates of transgenic mice. These chelators may work through simultaneous metal chelation and peptide modification to interfere with the Aβ aggregation. Such an intramolecular synergism distinguishes PC1 and PC2 from other chelators as potential anti-AD agents. This journal is © 2012 The Royal Society of Chemistry.

A 4d-4f heterometallic coordination polymer, [AgNd(pydc) 2]·2H 2O (1) (H 2pydc=pyridine-3,4- dicarboxylic acid), was synthesized under hydrothermal conditions, and further characterized by elemental analysis, IR, thermogravimetric analysis and single-crystal X-ray diffraction. Complex 1 featured a three-dimensional (3D) framework containing one-dimensional (1D) channels occupied by free water molecules, which was constructed from 1D inorganic heterometallic chains and linear pydc linkers. To our knowledge, complex 1 represented a rare example of 3D open-framework 4d-4f heterometallic coordination polymer. After removal of the water molecules from complex 1, the remaining material had high thermal stability. Moreover, the near-infrared luminescent properties of 1 were also investigated in the solid state. © 2012 The Chinese Society of Rare Earths.

A method to enhance the relaxation oscillation frequency and carrier bandwidth of a delayed feedback semiconductor laser transmitter is presented using additive optical feedback light. A formula for frequency detuning of the optical dual-feedback is developed to demonstrate that frequency detuning is added with the additive optical feedback light level. The function of the relaxation oscillation frequency of the chaotic laser is theoretically determined to show that it can be broadened by including the delay time and feedback level. Numerical results demonstrate that the bandwidth with the additive optical feedback light can be enhanced 1.7 times more than the bandwidth without it and the relaxation oscillation frequency of the chaotic laser is increased to 1.8 times more than that of the laser without it. The current can enhance the relaxation oscillation frequency and bandwidth of the transmitter more efficiently. © 2010 Elsevier B.V. All rights reserved.

Yan S.-L.,Nanjing Xiaozhuang University
Wuli Xuebao/Acta Physica Sinica | Year: 2013

We present a "master-slave-response" synchronization system of chaotic multiple-quantum-well lasers. And we study the applications of chaotic parallel synchronization for optical logic gates. An injection multiple-quantum-well laser drives two responding systems of multiple-quantum-well lasers to obtain chaotic synchronization while the injection multiple-quantum-well laser can synchronize the responding systems. We present theoretically the constructions of the fundamental all-optical gates based on the parallel synchronization of responding systems and define their computational principle. By modulating the driving light into the responding systems, all-optical logic gates characterizing logic function are realized by synchronizing or unsynchronizing appropriately the two chaotic states of responding systems. We present all-optical XNOR, NOR, NOT logic gates and their logic computational methods. Numerical simulation result validates the feasibility of the system. © 2013 Chinese Physical Society.

Zhang X.,Nanjing Xiaozhuang University
Guangxue Xuebao/Acta Optica Sinica | Year: 2011

Based on the Snyder-Mitchell model that describes the paraxial beam propagating in strongly nonlocal nonlinear media and the trial solution with modulating the Gaussian beam by the parabolic cylinder functions, the close forms of elegant Hermite-Gaussian beams (EHGB) are accessed in Cartesian coordinate system. The collinear EHGB will evolve to be the rotating charge vortex EHGB on certain condition. It is shown that the transferring of the single EHGB and the rotating charge vortex EHGB at the critical power. The widths of the profiles of the breathers and the rotating charge vortex breathers are varied periodically in the transferring.

A novel coordination polymer, [Co 3(bta) 2(dib)2] ·4H 2O (1, H 3bta = benzene-1,3,5-triacetic acid, and dib = 1,4-di(1H-imidazol-1-yl)benzene), has been hydrothermally prepared and characterized by IR spectroscopy, elemental analysis and single-crystal X-ray diffraction. The crystal is of triclinic system, space group P1̄, with a = 9.141(2), b = 9.667(2), c = 13.855(2) Å, α = 100.83(3), β = 90.81(3), γ = 100.94(3)°, V = 1179.0(4) Å 3, C 48H 46N 8O 16Co 3, M r = 1167.72, D c = 1.645 g/cm 3, F(000) = 599, μ = 1.127 mm -1 and Z = 1. The final R = 0.0634 and wR = 0.1703 for 4291 observed reflections (I > 2σ(I)). In the title complex, the bta ligand acts as a four-dentate bridging ligand to link up cobalt atoms into a lamellar framework, which are further interlinked by the dib ligands to generate a binodal (3,8)-connected tfz-d net.

Zhang X.,Nanjing Xiaozhuang University
Guangxue Xuebao/Acta Optica Sinica | Year: 2012

Based on the modified Snyder-Mitchell model the transmission of the optical vortex soliton that is produced by two collinear Laguerre-Gaussian solitons (CLGS) in strongly nonlocal nonlinear media is studied. Under certain condition, the profiles of the optical vortex solitons will rotate in transmiting with the beam width unvarying, which are named rotating vortex solitons, and can be explained by the Gouy phase in superposed light field. A few rotating vortex solitons are shown and the many-ring rotating vortex solitons are accessed in strongly nonlocal nonlinear media.

Yan S.-L.,Nanjing Xiaozhuang University
Wuli Xuebao/Acta Physica Sinica | Year: 2010

A novel method of bandwidth enhancement of a chaotic carrier from a semiconductor laser transmitter is studied by cross-phase modulation (XPM). And a physical model of laser dynamics is presented under the condition of XPM effect of optical fiber path. A frequency detuning formula with optical dual-feedback and XPM effect is deduced. The nonlinear phase shift arisen from XPM effect impacts on the gain and bandwidth enhancement factor of the laser. The second order nonlinear effect of the fiber enriches the varieties in the amplitude and the phase of the laser while the nonlinear phase shift produces a lot of new frequencies, which spread the bandwidth. Numerical results reveal that, with XPM effect, the new bandwidth is the quadruple of the bandwidth without XPM effect, and the relaxation oscillation frequency of the chaotic laser is increased to 2.85 times that of the laser without XPM effect. It is found that the enhancement of the chaotic bandwidth depends evidently on the optical fiber length, the power input into the optical fiber, the mirror reflectance and the second order nonlinear coefficient. © 2010 Chin. Phys. Soc.

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