钛表面钠氢氧钛纳米线的结构、生物活性和MC3T3-E1细胞响应

采用化学方法处理微弧氧化(MAO)制备的含Si、Ca元素的Ti O2涂层(SC),获得钛氢氧钠(Na0.8H1.2Ti3O7)生物活性纳米线结构。化学处理过程中,SC涂料表面出现了Ca、Na元素溶解,Si元素沉积的现象。化学处理后的SC涂层比SC涂料具有更好的吸水性和诱导磷灰石形成能力。这与处理后涂层(SHTO)特殊的纳米结构有关,在模拟体液浸泡过程中更容易形成Ti-OH。同时,钠氢氧钛纳米线的表面形貌、相组成、OH基团以及良好的湿润能力使其更加适合于MC3T3-E1细胞的粘附和增值。     

Six‐wave mixing induced by free‐carrier plasma in silicon nanowire waveguides

Nonlinear wave mixing in mesoscopic silicon structures is a fundamental nonlinear process with broad impact and applications. Silicon nanowire waveguides, in particular, have large third‐order Kerr nonlinearity, enabling salient and abundant four‐wave‐mixing dynamics and functionalities. Besides the Kerr effect, in silicon waveguides two‐photon absorption generates high free‐carrier densities, with corresponding fifth‐order nonlinearity in the forms of free‐carrier dispersion and free‐carrier absorption. However, whether these fifth‐order free‐carrier nonlinear effects can lead to six‐wave‐mixing dynamics still remains an open question until now. Here we report the demonstration of free‐carrier‐induced six‐wave mixing in silicon nanowires. Unique features, including inverse detuning dependence of six‐wave‐mixing efficiency and its higher sensitivity to pump power, are originally observed and verified by analytical prediction and numerical modeling. Additionally, asymmetric sideband generation is observed for different laser detunings, resulting from the phase‐sensitive interactions between free‐carrier six‐wave‐mixing and Kerr four‐wave‐mixing dynamics. These discoveries provide a new path for nonlinear multi‐wave interactions in nanoscale platforms.

     

双层分等级TiO_2纳米线制备及其光伏性能研究

采用两步溶剂热反应制备了底层为分等级锐钛矿的TiO_2纳米线阵列,上层为分等级锐钛矿的TiO_2纳米线薄膜的双层结构电极.通过XRD和SEM对其组成和形貌进行了表征,并考察了纳米线薄膜对染料敏化太阳电池(DSSC)光伏性能的影响.实验结果表明,分等级锐钛矿的TiO_2纳米线作为DSSC的光阳极,光电转换效率为4.39%,其效率高于光滑的TiO_2纳米线光阳极电池效率(2.07%).     

Well-dispersed sulfur anchored on interconnected polypyrrole nanofiber network as high performance cathode for lithium-sulfur batteries

Preparation of novel sulfur/polypyrrole (S/PPy) composite consisting well-dispersed sulfur particles anchored on interconnected PPy nanowire network was demonstrated. In such hybrid structure, the as-prepared PPy clearly displays a three-dimensionally cross-linked and hierarchical porous structure, which was utilized in the composite cathode as a conductive network trapping soluble polysulfide intermediates and enhancing the overall electrochemical performance of the system. Benefiting from this unique structure, the S/PPy composite demonstrated excellent cycling stability, resulting in a discharge capacity of 931 mAh g⁻¹ at the second cycle and retained about 54% of this value over 100 cycles at 0.1 C. Furthermore, the S/PPy composite cathode exhibits a good rate capability with a discharge capacity of 584 mAh g⁻¹ at 1  C.     

Preparation and characterization of gold nanoparticles and nanowires loaded into rod-shaped silica by a one-step procedure

Rod-shaped mesoporous silica nanoparticles (RMSN) with built-in gold nanoparticles or thin gold nanowires in the pore channels were in situ synthesized via a one-step procedure. The insertion of a hydrophobic gold precursor into the mesopores of RMSN was reached through a micellar solubilization mechanism and gold nanoparticles were achieved through a thermal reduction. The resulting RMSN and Au-RMSN samples were characterized by using X-ray diffraction, transmission and scanning microscopies (TEM and SEM), X-ray photoelectron spectroscopy (XPS), nitrogen physisorption and solid-state Nuclear Magnetic Resonance (NMR). The interaction of Au precursor (a carbene complex) with the thiol group at the silica surface was identified and found to play a crucial role in the dispersion of the uniform metal nanoparticles at the internal surface of RMSN. Moreover, TEM micrographs revealed the absence of large gold particles outside the mesopore network. The shape of Au nanoparticles and their loading amount in the mesoporous silica could be easily tuned by altering the concentration of gold precursor.     

On the stability of tangent bundle on double coverings

Let Y be a smooth projective surface defined over an algebraically closed field k with char k≠2, and let π : X →Y be a double covering branched along a smooth divisor. We show that y_X is stable with respect to π~*H if the tangent bundle y_Y is semi-stable with respect to some ample line bundle H on Y.     

Recent progresses on solution-processed silver nanowire based transparent conducting electrodes for organic solar cells

Organic photovoltaics (OPVs) are considered as a future alternative for conventional silicon based solar cells, owing to their low cost, ease of production and high-throughput. The transparent conducting electrode (TCE) is a fundamental component of OPVs. Traditionally, indium tin oxide (ITO) has been mainly utilized as a TCE in OPV applications due to its relatively high transparency and low sheet resistance. However, increasing demand for the optoelectronic devices has led to large fluctuations in ITO prices in the past decade and ITO is known to account more than 50% of the total cost of OPV devices. Thus, it is believed that development of solution-processable alternative materials is of great importance in reducing the cost of OPVs. Numerous materials, including silver nanowires, carbon nanotubes, graphene and conducting polymers, have been offered as replacements for ITO. This article reviews recent progress on fabrication of TCE via solution based coating techniques of silver nanowires (Ag NWs). In addition, performance of the Ag NWs based TCE in OPVs is summarized. Finally, we explore the future outlook for Ag NWs based TCE at the end of the review.     

GEOMETRIC FRAMEWORK AND MINIMAL REALIZATIONS OF NONLINEAR SYSTEMS ON FIBRE BUNDLE

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Immiscible Displacement in the Interacting Capillary Bundle Model Part I. Development of Interacting Capillary Bundle Model

An interacting capillary bundle model is developed for analysing immiscible displacement processes in porous media. In this model, pressure equilibration among the capillaries is stipulated and capillary forces are included. This feature makes the model entirely different from the traditional tube bundle models in which fluids in different capillaries are independent of each other. In this work, displacements of a non-wetting phase by a wetting phase at different injection rates were analysed using the interacting capillary bundle model. The predicted evolutions of saturation profiles were consistent with both numerical simulation and experimental results for porous media reported in literature which cannot be re-produced with the non-interacting tube bundle models.     

Harmonic behavior of silicon nanowire by molecular dynamics

Silicon nanowires (SiNW) have attracted increasing interests as potential core parts for nanoscale devices due to their distinguished mechanical and electrical properties. Using molecular dynamics (MD) method, we investigated the vibration behaviors of SiNW on the atomic scale, including the fundamental mode frequency and quality factor. The quality factor as low as 120 is attributed to the energy loss process coming from atomic friction and nonlinearity. We also found that the energy of lattice vibration (phonon energy) is much larger than the macroscale beam vibration energy. And both the energies are less than the surface relaxation energy of the beam. The comparison between MD and FEM has been made to discuss the validity of continuum approximation for the study of SiNW.