Two-dimensional self-organization of 1-nonanethiol-capped gold nanoparticles

A two-dimensional (2D) ordered hexagonal close-packed structure, formed by 1-nonanethiol-capped gold nanoparticles, is reported. The structure was constructed only by dipping the gold nanoparticle colloidal solution on flat substrate. The gold nanoparticles were synthesized as follows: First, AuCl₄^-1 was transferred from aqueous solution to toluene by the phase-transfer reagent of tetraoctylammonium bromide. Then it was reduced with aqueous sodium borohydride in the presence of a given amount of 1-nonanethiol molecules which was used to control the nucleation and growth of the gold nanoparticles for the desired size. The experimental techniques, such as UV-Vis, FT-IR, and X-ray photoelectron spectroscopy (XPS), were employed to characterize the obtained product. Transmission electron microscopy (TEM) measurement demonstrated the size of the gold nanoparticle and the formation of two-dimensional ordered hexagonal close-packed gold nanoparticle structure.     

AM ultrasound-modulated optical tomography with realtime FFT

We report on a novel ultrasound-modulated optical tomographic technique applied in dense tissue-simulating turbid media. A 1 MHz ultrasound beam is focused into the media to modulate and tag the scattering laser light passing through the ultrasonic focused zone. A 10 kHz sinusoidal wave, as a detection wave, is carried by the ultrasound beam through amplitude-modulation (AM). The scattering photons that come from the focused zone carry the modulated information, received by detector and demodulated by real-time fast Fourier transform (FFT). The optical tomographic images of the tissue simulating media and buried object are reconstructed with AM spectral intensity. This method can be applied to imaging three-dimensional tissue structures with different optical parameters. For the first time, we obtained the tomography of buried objects in biological tissue phantoms with a detecting depth of 30 mm.     

修正的Black—Scholes期权定价模型

在期权有效期内σ,r,D0是时间t的已知函数下,得到了欧式期权的B－S定价方程的解,从而获得了欧式看涨和看跌期权的定价公式。     

不可逆斯特林热泵的优化性能

建立以理想气体或范德瓦尔斯气体为工质的不可逆斯特林热泵模型,考虑热阻、回热损失及回热过程时间对斯特林泵热泵的影响,导出泵热率与性能系数间的优化关系,并讨论了斯特林热泵的其它优化性能。     

电磁分离降低铝硅合金中铁含量

利用电磁分离法去除铝熔体中初生富铁相,以降低合金中铁含量,并在自制电磁分离实验装置上对A-12%S-1.1F-1.2%Mn熔体进行连续电磁分离,结果表明,经过一次电磁分离使熔体中＞10um的初生富铁相全部去除,铁含量从1．13％降低到0．67％,而处理后的合金重熔凝固后仍然形成大量初生富铁相,再次进行电磁分离处理则使铁含量进一步降低到0．41％,Fe铝熔体中扩散和富铁相的凝固特性决定需要两次以上电磁分离才能有效地降低合金中铁含量,达到了铝硅合金工业生产的需要。     

3个Ramsey数R(4,q)的新下界

使用新的方法搜索Ramsey数（R（4,q)的下界,获得R（4,20)≥234,R(4,22)≥314,R(4,25)≥458     

前馈控制方法在非轴对称表面加工中的应用

解决非轴对称曲面的车削加工控制中压陶瓷伺服刀架的滞后问题,消除加工中的滞后误差,在分析压电陶瓷刀具迟滞缺点的基础上建立了3种消除迟滞误差的前馈控制数据模型,即：升压模型,峰值降压模型及任意点降压模型,用这些数字模型进行补偿加工实验,最大位移误差为0．05um,补偿前后的加工精度对比表明,采用前馈控制补偿的加工方法能够大大降低加工中的迟滞误差,提高非轴对称曲面的加工精度。     

求解相容的矩阵方程组A1XB1＝D1，A2XB2＝D2的一种迭代法

给出了求解矩阵方程组A1XB1＝D1,A2XB2＝D2的迭代法。     

射孔斜井产能预测新方法

从Besson公式的基础上引入双径向流模型,采用等值渗流阻力法,分射穿污染带与未射穿污染带两种情况推导出射孔斜井的产能公式。考虑了孔深、孔密、孔径、相位、污染带的半径与污染程度、压实带的厚度与压实程度、井斜角等因素对产能的影响。利用本文所推导的公式对射孔斜井产能进行参数敏感性分析,认为:产能指数对井斜角、孔深、孔密、压实程度、相位、孔径、压实带厚度的敏感性依次降低;产能指数对射孔参数和压实带参数的敏感性在未射穿污染带时比射穿污染带时高。     

MOCVD法制备TiO_2薄膜的光电化学性质研究

采用金属有机化学气相沉积 (MOCVD)法制备了TiO2 薄膜 ,测定了TiO2 薄膜的晶体结构 ,以 p -Si为基底电极 ,研究了TiO2 薄膜的光电化学性质 .经TiO2 修饰的p-Si电极 ,开路光电位增加近 2 0倍 ,并表现出很强的稳定性 ,是较理想的光电极材料及光电极修饰材料 .