近红外光谱快速测定红花逆流提取过程中羟基红花黄色素A的含量

采用近红外光谱(NIRS)透射法对红花罐组式逆流提取过程中羟基红花黄色素A(Hydroxysafflor yellow A,HSYA)的含量进行快速无损的测定.在红花逆流提取过程中,以高效液相色谱法(HPLC)为对照分析方法,测定提取液中羟基红花黄色素A的含量,运用偏最小二乘(PLS)法建立NIR光谱与羟基红花黄色素A的HPLC分析值之间多元校正模型,并对逆流提取过程的未知样本进行含量预测.校正模型相关系数达到0.982,预测相关系数达到0.965,RMSEC和RMSEP分别为0.053和0.075,RSEC和RSEP分别为3.96%和5.25%.结果表明,NIRS可以作为一种准确、快速、无损的检测方法用于检测中药逆流提取过程有效成分含量变化规律.     

高效液相色谱法测定红花中的羟基红花黄色素A

建立了菊科植物红花中的主要有效成分羟基红花黄色素A的高效液相色谱定量分析方法。用90 ℃水提取,以甲醇-0.5%磷酸水溶液(体积比为40∶60)为流动相,检测波长400 nm。该方法的最低检出限为4 ng (按S/N=3计)。在羟基红花黄色素A的质量浓度为0.04-0.40 g/L(相当于绝对进样量为0.8-8.0 μg)时线性良好,方法回收率高,重现性好。对26个不同产地和购买地的红花中的羟基红花黄色素A进行了测定,结果表明不同来源的红花中羟基红花黄色素A含量的差异较大。     

RP-HPLC测定十四味羚牛角丸中羟基红花黄色素A的含量

应用高效液相色谱的方法建立藏药十四味羚牛角丸中羟基红花黄色素A的定量分析.色谱条件:用Symmetry C18(5μm,4.6×250 mm);流动相:V(甲醇):V(水):V(H3PO4)=26:74:0.05,检测波长:403 nm,流速:1.0mL/min,羟基红花黄色素A在6～96μg/mL范围内呈良好线性关系,r=0.9996,十四味羚牛角丸中羟基红花黄色素A的回收率为99.24%(RSD=1.9%,n=5).本方法简便、快速、准确、灵敏度高、重现性好,可用于藏药十四味羚牛角丸中羟基红花黄色素A的含量测定.     

脉冲阳极氧化条件对多孔硅法布里-珀罗干涉特性影响

采用电化学脉冲阳极氧化法制备具有干涉效应的多孔硅. 研究电流密度、有效阳极氧化时间、电解液组成对多孔硅法布里-珀罗(F-P)干涉特性的影响, 利用光纤光谱仪测量多孔硅反射光谱并计算其光学厚度. 结果表明, 当阳极氧化电流密度78 mA•cm－2、有效阳极氧化时间5 min、氢氟酸与乙醇体积比VHF∶VEtOH＝2∶1时, 制备的多孔硅法布里-珀罗干涉条纹均匀, 膜层性质稳定; 当与饱和乙醇气体接触时, 多孔硅反射光谱吸收峰位由612红移到637 nm, 光学厚度由5864增加到6296 nm, 表明利用多孔硅法布里-珀罗干涉效应检测乙醇气体思路是可行的.     

高效液相色谱法测定藏药萨热大鹏丸中羟基红花黄色素A

用反相高效液相色谱法测定藏药萨热大鹏丸中的羟基红花黄色素A。C18色谱柱(4.6 mm×250 mm,5μm);流动相:甲醇-0.05%H3PO4溶液,梯度洗脱;流速:1 mL/min;柱温25℃;检测波长为403 nm。羟基红花黄色素A在0.11136~0.94654μg的范围内呈线性关系,回归方程为y=2435.7402x-10.9502,r=0.9999;平均加样回收率为99.9%,RSD为0.3%。该方法可用于萨热大鹏丸中羟基红花黄色素A的测定。     

高效液相色谱法测定九味石灰华散中羟基红花黄色素A和红景天苷的含量

建立了测定中药复方制剂九味石灰华散中羟基红花黄色素A和红景天苷含量的高效液相色谱方法.采用Kromasil C18色谱柱(5μm,250 mm×4.6 mm),以乙腈∶0.1%磷酸溶液(12∶88,V/V)为流动相,流速1.0 mL/min,羟基红花黄色素A的检测波长为403 nm,红景天苷的检测波长为275 nm.羟基红花黄色素A和红景天苷分别在0.288~180μg/mL和4.8~1 200μg/mL范围内呈良好的线性关系(r值为0.999 8~0.999 9),最低检出限分别为0.03μg/mL和0.5μg/mL(S/N=3),加标回收率分别为95.7%~97.4%和95.9%~98.6%.该方法简便、准确、重现性好,可用于九味石灰华散的质量控制.     

量子限制效应对多孔硅液相电致发光的影响

着重研究多孔硅在阴极偏压下过硫酸铵溶液中电压调制的电致发光现象 .随阴极偏压的增大 ,电致荧光峰位蓝移 ,荧光强度增大 ,同时发现定电压下 ,发生电致发光随时间的衰减伴随着光谱的红移现象 .通过红外光谱、AFM及电化学等手段对电致发光的电位调制机理及荧光衰减机制进行了研究 ,结果表明电致发光与光致发光具有相同的起源 ,电压选择激发不同粒径的多孔硅 ,而导致了发光峰值能量的电位选择性 .在电致发光过程中 ,强氧化剂向多孔硅注入空穴使其表面氧化导致小粒径的硅晶逐渐被剥落 ,使光谱高能部分首先衰减出现了随时间的电致发光红移现象 .这些结果支持量子限制效应在多孔硅液相电致发光中起着重要作用     

多孔硅微腔的光学特性和环境污染物检测

利用电化学刻蚀,制备了由一个Fabry-Perot微腔夹于两个Bragg反射镜中的多孔硅微腔光学晶体.扫描电子显微镜（SEM）清晰揭示了这种结构的＂三明治＂式物理构造.通过改变阳极氧化参数,可以调节这种结构的光学特性.而通过合适的热氧化和表面化学修饰,这种结构可以用于环境污染物（如挥发性有机物乙腈、甲苯、环己烷、三氯甲烷、丙酮、乙醇的蒸汽和室内装修气体甲苯、氨气、甲醛）的光学传感检测.其中,热氧化和化学修饰过程由傅里叶红外光谱（FTIR）得以证实,而传感过程则通过修饰后的多孔硅微腔对目标分析物的光学响应得以实现.这种基于多孔硅微腔的光学传感器具有良好的稳定性、敏感性和选择性,因此在气体传感和环境检测中具有广阔的应用前景.     

吸附钌吡啶类配合物染料分子对氧化多孔硅光致 发光性质的影响

化学氧化多孔硅经cis-Ru(bpy)~2(CN)~2的乙醇溶液浸泡后,发光峰位红移,强度减弱,激发态寿命缩短。而在trans-Ru(py)~4(CN)~2溶液中浸泡的氧化多孔硅的发光峰位,强度和寿命几乎没有变化。对比两个染料分子的氧化还原电位和光吸收性质得出：与trans-Ru(py)~4(CN)~2相比,cis-Ru(bpy)~2(CN)~2有一个与多孔硅发光能量接近的低能级吸收带,使得多孔硅纳米粒子向该染料分子传递能量成为可能,能量传递的发生引起了发光峰位的红移和激发态寿命的缩短,虽然伴随着发光效率的损耗,但对有目的地选择染料分子来改变多孔硅的发光峰位和获得激发态寿命尽可能小的多孔硅提供了思路,也为深入理解多孔硅的光致发光机制提供了更多的实验事实。     

吸附钌吡啶类配合物染料分子对氧化多孔硅光致发光性质的影响

化学氧化多孔硅经cis-Ru(bpy)~2(CN)~2的乙醇溶液浸泡后,发光峰位红移,强度减弱,激发态寿命缩短。而在trans-Ru(py)~4(CN)~2溶液中浸泡的氧化多孔硅的发光峰位,强度和寿命几乎没有变化。对比两个染料分子的氧化还原电位和光吸收性质得出：与trans-Ru(py)~4(CN)~2相比,cis-Ru(bpy)~2(CN)~2有一个与多孔硅发光能量接近的低能级吸收带,使得多孔硅纳米粒子向该染料分子传递能量成为可能,能量传递的发生引起了发光峰位的红移和激发态寿命的缩短,虽然伴随着发光效率的损耗,但对有目的地选择染料分子来改变多孔硅的发光峰位和获得激发态寿命尽可能小的多孔硅提供了思路,也为深入理解多孔硅的光致发光机制提供了更多的实验事实。     

Optical properties of passivated silicon nanoclusters: the role of synthesis

The effect of preparation conditions on the structural and optical properties of silicon nanoparticles is investigated. Nanoscale reconstructions, unique to curved nanosurfaces, are presented for silicon nanocrystals and shown to have lower energy and larger optical gaps than bulk-derived structures. We find that high-temperature synthesis processes can produce metastable noncrystalline nanostructures with different core structures than bulk-derived crystalline clusters. The type of core structure that forms from a given synthesis process may depend on the passivation mechanism and time scale. The effect of oxygen on the optical of different types of silicon structures is calculated. In contrast to the behavior of bulklike nanostructures, for noncrystalline and reconstructed crystalline structures surface oxygen atoms do not decrease the gap. In some cases, the presence of oxygen atoms at the nanocluster surface can significantly increase the optical absorption gap, due to decreased angular distortion of the silicon bonds. The relationship between strain and the optical gap in silicon nanoclusters is discussed.     

Effects of Ultraviolet Illumination and Pre-treatments on Porous Silicon Formation

Although porous silicon is readily formed by anodizing silicon wafers in HF-based solutions, its application in silicon-based optoelectronic devices is greatly limited due to its poor stability and low luminescence yield. It is well recognized that the nature of silicon wafers and the fabrication condition parameters significantly influence uniformity, stability and optical properties of porous silicon. In this work, the ultraviolet illumination and pre-treatments were investigated for porous silicon formation. The surface morphologies and optical properties of the samples were also studied.     

Surface morphology dependent photoluminescence from colloidal silicon nanocrystals

Monodisperse 1-2 nm silicon nanocrystals are synthesized in reverse micelles and have their surfaces capped with either allylamine or 1-heptene to produce either hydrophilic or hydrophobic silicon nanocrystals. Optical characterization (absorption, PL, and time-resolved PL) is performed on colloidal solutions with the two types of surface-capped silicon nanocrystals with identical size distributions. Direct evidence is obtained for the modification of the optical properties of silicon nanocrystals by the surface-capping molecule. The two different surface-capped silicon nanocrystals show remarkably different optical properties.     

Dimensionality dependence of optical properties and quantum confinement effects of hydrogenated silicon nanostructures

The excited state properties of linear, planar, and spherical hydrogenated silicon nanostructures are studied systematically with use of a time-dependent Hartree-Fock (TDHF) approach with a semiempirical Hamiltonian. The calculated optical gaps decrease significantly from linear, planar, to spherical silicon structures, showing that the optical gap is dimensionality dependent and hence it can be varied by solely managing the shape of the nanostructures. Remarkably, the calculated exciton sizes of the lowest dipole-allowed excited states for both silicon chains and planes are approximately 26 A, revealing that the quantum confinement effect should be significantly enhanced when the sizes of silicon nanostructures are smaller than this value but not dependent on the dimensionality. A similar trend is also observed for hydrogenated silicon spherical clusters.     

Sliding Water Droplet on Oil Impregnated Surface and Dust Particle Mitigation

Self-cleaning of surfaces becomes challenging for energy harvesting devices because of the requirements of high optical transmittance of device surfaces. Surface texturing towards hydrophobizing can improve the self-cleaning ability of surfaces, yet lowers the optical transmittance. Introducing optical matching fluid, such as silicon oil, over the hydrophobized surface improves the optical transmittance. However, self-cleaning ability, such as dust mitigation, of the oil-impregnated hydrophobic surfaces needs to be investigated. Hence, solution crystallization of the polycarbonate surface towards creating hydrophobic texture is considered and silicon oil impregnation of the crystallized surface is explored for improved optical transmittance and self-cleaning ability. The condition for silicon oil spreading over the solution treated surface is assessed and silicon oil and water infusions on the dust particles are evaluated. The movement of the water droplet over the silicon oil-impregnated sample is examined utilizing the high-speed facility and the tracker program. The effect of oil film thickness and the tilting angle of the surface on the sliding droplet velocity is estimated for two droplet volumes. The mechanism for the dust particle mitigation from the oil film surface by the sliding water droplet is analyzed. The findings reveal that silicon oil impregnation of the crystallized sample surface improves the optical transmittance significantly. The sliding velocity of the water droplet over the thick film (~700 µm) remains higher than that of the small thickness oil film (~50 µm), which is attributed to the large interfacial resistance created between the moving droplet and the oil on the crystallized surface. The environmental dust particles can be mitigated from the oil film surface by the sliding water droplet. The droplet fluid infusion over the dust particle enables to reorient the particle inside the droplet fluid. As the dust particle settles at the trailing edge of the droplet, the sliding velocity decays on the oil-impregnated sample.     

Active particle control through silicon using conventional optical trapping techniques

Functional integration of optical trapping techniques with silicon surfaces and environments can be realized with minimal modification of conventional optical trapping instruments offering a method to manipulate, track and position cells or non-biological particles over silicon substrates. This technique supports control and measurement advances including the optical control of silicon-based microfluidic devices and precision single molecule measurement of biological interactions at the semiconductor interface. Using a trapping laser in the near infra-red and a reflective imaging arrangement enables object control and measurement capabilities comparable to trapping through a classical glass substrate. The transmission efficiency of the silicon substrate affords the only reduction in trap stiffness. We implement conventional trap calibration, positioning, and object tracking over silicon surfaces. We demonstrate control of multiple objects including cells and complex non-spherical objects on silicon wafers and fabricated surfaces.     

Time‐Resolved Synchrotron Radiation Excited Optical Luminescence: Light‐Emission Properties of Silicon‐Based Nanostructures

The recent advances in the study of light emission from matter induced by synchrotron radiation: X‐ray excited optical luminescence (XEOL) in the energy domain and time‐resolved X‐ray excited optical luminescence (TRXEOL) are described. The development of these element (absorption edge) selective, synchrotron X‐ray photons in, optical photons out techniques with time gating coincide with advances in third‐generation, insertion device based, synchrotron light sources. Electron bunches circulating in a storage ring emit very bright, widely energy tunable, short light pulses (<100 ps), which are used as the excitation source for investigation of light‐emitting materials. Luminescence from silicon nanostructures (porous silicon, silicon nanowires, and Si–CdSe heterostructures) is used to illustrate the applicability of these techniques and their great potential in future applications.     

Optical gap and excitation energies of small Ge nanocrystals

Using the density functional theory (DFT) with the hybrid nonlocal exchange correlation functional of Becke and Lee, Yang and Parr (B3LYP), we have calculated the optical gap and the oscillator strengths for several of the lowest, spin and symmetry allowed, electronic transitions of small Ge nanocrystals passivated by hydrogen. The largest nanoparticle has an approximate diameter of 2 nm. Our results show that the optical gap exhibits size dependence (due to quantum confinement) roughly similar to silicon nanoparticles. However, for this range of diameters, there is an indirect-to-direct transition in the spectra of Ge as the size of the nanocrystals decrease. The first allowed excitation (fundamental optical gap) of each germanium nanoparticle has relatively larger oscillator strengths compared to silicon. The diameter of the smallest Ge nanocrystal capable to emit in the visible region of the spectrum, is approximately 1.9 nm, compared to 2.2 nm for silicon nanocrystals.     

两步法制备多孔硅及其表征I:恒电流法(英文)

本工作通过采用电化学极 -化学氧化两步法在 1:1氢氟酸和乙醇溶液中制备出孔径约为 1～ 2 μm ,厚度大经为 6～ 10 μm的多孔硅样品 .首先将 0 .0 3A/cm2 的恒电流施加到p( 10 0 )硅片一段时间 ,然后将该硅片浸到 2 0 %的硝酸溶液中氧化一段时间 .通过此方法获得的多孔硅结构再进一步用扫描电子显微镜和拉曼光谱仪进行表面形貌和光学性质的考察 .所有制备出的多孔硅结构均有光致发光现象 .老化的多孔硅样品 (在干燥器放置一年 )的光致发光谱峰强度明显增强 ,但分别经过苯乙烯和十六碳烯 ( 1)两种有机溶剂处理 1h后的老化多孔硅样品的光致发光强度却没有显著改变 .