Label-Free and Real-Time Monitor of Binding and Dissociation Processes between Protein A and Swine IgG by Oblique-Incidence Reflectivity Difference Method

Life science has a need for detection methods that are label-free and real-time. In this paper, we have selected staphylococcal protein A （SPA） and swine immunoglobulin G （IgG）, and monitor the bindings between SPA and swine IgG with different concentrations, as well as the dissociations of SPA-swine IgG complex in different pH values of phosphate buffer by oblique-incidence reflectivity difference （OIRD） in a label-free and real-time fashion. We obtain the ON and OFF reaction dynamic curves corresponding to the bindings and dissociations of SPA and swine IgG. Through our analysis of the experimental results, we have been able to obtain the damping coefficients and the dissociation time of SPA and swine IgG for different pH values of the phosphate buffer. The results prove that the OIRD technique is a competing method for monitoring the dynamic processes of biomolecule interaction and achieving the quantitative information of reaction kinetics.

Label-free detection of hybridization of oligonucleotides by oblique-incidence reflectivity difference method

The microarrays of 20-base oligonucleotide with different concentrations are detected before and after hybridization by the oblique-incidence reflectivity difference (OI-RD) method. The experimental results prove that OI-RD is a label-free method which can not only distinguish the concentration difference of oligonucleotides before and after the hybridization but also detect the hybridization of short oligonucleotides. At present the OI-RD method can detect 0.39 μmol/L 20-base oligonucleotide or less. These results suggest that the OI-RD method is a promising and potential technique for label-free detection of biological microarrays.

Detection of hybridization of protein microarrays using an oblique-incidence reflectivity difference method

Mouse-Immunoglobulin G(mouse-IgG) with different concentrations in a range from 1000 to 0.0128 μg/mL and a specific hybridization with goat anti-mouse IgG were detected successfully by using an oblique-incidence reflectivity difference(OI-RD) method.Two detection signals,consisting of an imaginary part(Im{Δp-Δs}) and a real part(Re{Δp-Δs}) of OI-RD,were obtained simultaneously.The detection results of hybridization by OI-RD were in accord with that of traditional fluorescent scans.In particular,we label-freely detected the washed mouse-IgG microarray with a series of concentrations and acquired a linear correlation between OI-RD intensities and the protein concentrations in logarithmic coordinates.The detection sensitivity of OI-RD can reach 14 fg.These experimental results suggest that the OI-RD method has potential applications in proteomics and clinical diagnosis.

Label-free detection repeatability of protein microarrays by oblique-incidence reflectivity difference method

We examine the repeatabilities of oblique-incidence reflectivity difference(OIRD) method for label-free detecting biological molecular interaction using protein microarrays.The experimental results show that the repeatabilities are the same in a given microarray or microarray-microarray and are consistent,indicating that OIRD is a promising label-free detection technique for biological microarrays.

Label-free high-throughput and real-time detections of protein interactions by oblique-incidence reflectivity difference method

Selected Mouse IgG of 1 mg/mL as target was fabricated on microarray for 500 sample dots.Label-free and real-time reaction dynamic processes were detected between the microarrays with Goat Anti-mouse IgG of 0.02 mg/mL using the obliqueincidence reflectivity difference(OIRD)method.We obtained the reaction results and the reaction dynamic curves of 500 protein dots.In addition,we also used label-free detection of protein microarrays of 10080 sample dots,including BSA and different concentrations of Mouse IgG and Rabbit IgG,by OIRD.The obtained reaction results between the protein microarray with 1 mg/mL Goat Anti-mouse IgG and 1 mg/mL Goat Anti-rabbit IgG are reported herein.Experimental results show that OIRD can be not only label-free high-throughput detection method for biological microarrays but also label-free real-time detection in the interaction processes of biomolecules.

Applying Finite Difference Method to Simulate the Performance of a Perforated Breakwater Under Regular Waves

Using a discretized finite difference method, a numerical model was developed to study the interaction of regular waves with a perforated breakwater. Considering a non-viscous, non-rotational fluid, the governing equations of Laplacian velocity potential were developed, and specific conditions for every single boundary were defined. The final developed model was evaluated based on an existing experimental result. The evaluated model was used to simulate the condition for various wave periods from 0.6 to 2 s. The reflection coefficient and transmission coefficient of waves were examined with different breakwater porosities, wave steepnesses, and angular frequencies. The results show that the developed model can suitably present the effect of the structural and hydraulic parameters on the reflection and transmission coefficients. It was also found that with the increase in wave steepness, the reflection coefficient increased logarithmically, while the transmission coefficient decreased logarithmically.

Label-free and real-time detection of antigen-antibody interactions by Oblique-incidence Reflectivity Difference(OIRD) method

We label-free and real-time detected three interaction processes of antigen-antibodies,Human Immunoglobulin G(IgG),Rabbit IgG,and Mouse IgG as the targets,and Goat Anti-human IgG,Goat Anti-rabbit IgG,and Goat Anti-mouse IgG as the probe,by the Oblique-incidence Reflectivity Difference(OIRD) method.The interaction dynamic curves of the OIRD signal,corresponding to the interaction processes of antigen-antibodies,are generated.The reaction times from beginning to equilibrium state are about 1800,900,and 1200 s for Human IgG,Rabbit IgG,and Mouse IgG,respectively.The experimental results demonstrate that the OIRD method not only can distinguish biomolecular interactions,but also can be used in real-time detection of interactions and dynamic processes of biomolecules.

Detection of protein microarrays by oblique-incidence reflectivity difference technique

Biological microarrays with different proteins and different protein concentrations are detected without external labeling by an oblique-incidence reflectivity difference (OIRD) technique. The initial experiment results reveal that the intensities of OIRD signals can distinguish the different proteins and concentrations of protein. The OIRD technique promises feasible applications to life sciences for label-free and high-throughput detection.

锗基长波红外圆锥形微结构减反射性能

锗是重要的红外光学材料,为减小锗表面的菲涅耳反射损耗,提高光利用率,研究了锗基底圆锥形微结构的减反射性能。基于时域有限差分法(Finite Difference Time Domain),并采用单因素法研究了微结构的占空比、周期、高度等结构参数与入射角在8~12μm长波红外波段对反射率的影响,确定了微结构在低反射情况下较优的结构参数组合,其在整个波段范围内的平均反射率低于1%,远低于平板锗结构的35.47%,在9~11μm的波段范围内反射率低于0.5%,且光波在40°范围内入射时,圆锥形微结构的平均反射率仍然较低。将优化的圆锥形微结构与平板结构进行了对比,从等效折射率、反射场分布和能量吸收分布3方面进一步证实了圆锥形微结构在整个波段范围内优异的减反射性能。

斜坡叠加起伏海床对波浪反射的修正缓坡方程有限差分解

基于修正缓坡方程,建立了方程求解的有限差分模型,研究了斜坡叠加起伏海床对波浪的反射.首先,对波浪入射平面斜坡以及水平海床上单周期、双周期正弦沙纹的反射问题进行了验证,结果与他人的数值解、解析解及实验数据吻合较好,证明了该模型的正确性.接着,讨论了抛物形斜坡的上凸高度及下凸深度,斜坡叠加单周期正弦沙纹的数量、高度及长度,斜坡叠加双周期正弦沙纹的高度对波浪反射系数的影响.结果表明,反射系数随抛物形斜坡上凸高度的增大而减小,随下凸深度的增大而增大.斜坡叠加单周期正弦沙纹对波浪反射的规律与水平海床基本一致,相比水平海床Bragg共振相位下移的幅度随沙纹数量增加,先减小后保持不变的情况,斜坡叠加沙纹共振相位下移的幅度随沙纹数量增加先减小后增大.波浪入射斜坡叠加双周期正弦沙纹地形,随叠加的两个沙纹高度分别增加,Bragg共振峰值均相应地增加,共振带宽几乎不受影响,主振峰值的相位下移幅度减小,这与单周期沙纹中随沙纹高度增加,共振相位下移幅度更大的情况相反.对比发现:当固定沙纹的数量、长度、高度,不论是水平海床还是斜坡海床,双周期正弦沙纹对波浪的反射强度以及激发的共振带宽均大于单周期正弦沙纹,共振相位下移的幅度则小于单周期沙纹;斜坡叠加正弦沙纹对波浪的反射强度要大于水平海床,零反射的现象不再存在,主振峰值的相位下移幅度较水平海床更大.

融合FDTD与遗传算法的高精度光学薄膜优化

该研究提出一种融合时域有限差分法(FDTD)和遗传算法的优化框架,旨在提高光学薄膜的反射性能。选择三层薄膜结构作为研究对象,通过使用FDTD方法计算薄膜结构的反射率,并将其作为遗传算法中的适应度函数。通过两者结合,在多维设计空间中有效搜索到了优化参数,显著降低了薄膜的反射率。这一方法不仅降低了计算成本,还提供了一种灵活且可扩展的解决方案,对未来高性能光学系统的设计和优化具有重要的实际意义。

Modeling bidirectional reflection distribution function of microscale random rough surfaces

The radiative properties of three different materials surfaces with one-dimensional microscale random roughness were obtained with the finite difference time domain method(FDTD) and near-to-far-field transformation.The surface height conforms to the Gaussian probability density function distribution.Various computational modeling issues that affect the accuracy of the predicted properties were discussed.The results show that,for perfect electric conductor(PEC) surfaces,as the surface roughness increases,the magnitude of the spike reduces and eventually the spike disappears,and also as the ratio of root mean square roughness to the surface correlation distance increases,the retroreflection becomes evident.The predicted values of FDTD solutions are in good agreement with the ray tracing and integral equation solutions.The overall trend of bidirectional reflection distribution function(BRDF) of PEC surfaces and silicon surfaces is the same,but the silicon's is much less than the former's.The BRDF difference from two polarization modes for the gold surfaces is little for smaller wavelength,but it is much larger for the longer wavelength and the FDTD simulation results agree well with the measured data.In terms of PEC surfaces,as the incident angle increases,the reflectivity becomes more specular.

Polarization insensitivity electromagnetically induced reflection in graphene metasurface

The electromagnetically induced reflection(EIR)effect of graphene metamaterials has been investigated by finite difference time domain(FDTD)method.In this study,a metamaterial sandwich structure composed of silica(SiO2),gold and graphene on terahertz band is designed.By changing the width of the two ribbons of graphene length and the incident angle of electromagnetic wave,the EIR effect of the structure is discussed,and it can be found that SiO2 is a kind of excellent dielectric material.The simulation results show that graphene metamaterial is not sensitive to polarized incident electromagnetic wave.Therefore,such EIR phenomena as insensitive polarization and large incident angle can be applied to optical communication filters and terahertz devices.

崎岖海底对下伏水平地层反射波特征的影响

在海洋地震勘探中,剧烈的海底起伏和速度差对下伏地层反射波运动学和动力学特征均产生较大影响。本文针对崎岖海底建立了海底大陡坡模型、海底坳陷模型、海底隆起模型和海底火山模型,并通过交错网格下优化的八阶精度有限差分法和优化的四阶精度Runge-Kutt(RK)法模拟研究了崎岖海底对下伏水平地层反射波特征的影响。数值算例表明:海底大陡坡、海底坳陷和海底隆起不仅使下伏水平地层的反射波和转换波发生畸变不再是标准的双曲线,而且影响反射波能量分布,从而容易造成构造假象;海底火山使下伏水平地层的反射波和转换波发生了更加复杂的畸变,给海洋地震勘探的数据处理和解释带来困难。

基于二维光子晶体的四通道滤波器设计

为实现光电信息器件的高集成度和高效输出,提高光电信息处理能力,设计了一种基于二维光子晶体的四通道滤波器,根据4个点缺陷微腔与线缺陷波导耦合原理,引入反射异质结并调整微腔与反射结的距离,提高输出效率,对滤波器1403、1426、1449、1508 nm四波长的波分复用功能进行仿真。仿真结果表明:该器件可实现高效传输,四波长透射率均超过95%,插入损耗均小于0.23 dB,通道间串扰均小于-8.7 dB。

锚杆动测问题的数学物理模型及实验分析

锚杆动测问题可归结为一维波动方程在不同初始条件和边界条件下的解的问题。本文在前人研究的基础上分析了锚杆一维纵向振动模型的数学物理方程,并根据物理状态给出了定解条件,对端头自由、底端固定的锚杆锚固状态给出了基于有限差分数值模拟方法,给定3种不同瞬态激振响应模型,从解的位移、加速度响应来看,基于雷克子波激振响应的数值模拟解是稳定的,对比模型锚杆检测结果来看,数值模拟解是可靠的,以锚杆一维纵向振动模型建立的声波反射法理论体系是自洽的。

4种遥感数据时空融合模型生成高分辨率归一化植被指数的对比分析

【目的】针对时空融合方法在遥感植被状况调查及动态变化监测中的应用,比对时空自适应反射率融合模型(STARFM)、增强型时空自适应反射率融合模型(ESTARFM)、回归拟合空间滤波和残差补偿模型(Fit-FC)和规则集回归树融合模型(RPRTM)等4种时空融合模型对归一化植被指数(NDVI)的融合效果。【方法】以三江源地区2块具有差异性地表特征的区域为研究样地,采用上述4种时空融合方法,融合空间分辨率30 m的Landsat 8影像和250 m时间步长16 d的MODIS NDVI数据,生成步长为16 d的30 m空间分辨率的NDVI数据。基于Landsat NDVI影像通过定性的目视判别和定量的统计分析来评价不同融合模型结果的空间特征模拟效果,并以真实的MODIS NDVI时间动态为参考,分析了不同融合方法对地表植被动态特征的拟合效果。【结果】(1)关于空间特征的捕捉,在地表覆盖状况较复杂的区域,RPRTM融合效果最佳(R2=0.82);而对于输入影像差异较大的区域,ESTARFM融合效果最佳(R2=0.95)。(2)关于时间动态的捕捉,RPRTM针对不同的植被型均取得了最佳效果(R2为0.97~0.99)。(3)相对于模型输入数据的时空可比性,地表异质性对STARFM和ESTARFM融合效果的影响更大。【结论】4种时空融合模型能有效用于生成高时空分辨率的NDVI数据,不同模型其融合效果各有不同,RPRTM在复杂地表区域与模拟植被生长动态变化中均有较好表现。

地震反射波波前法射线追踪

利用有限差分法解程函方程，分别求出震源点及接收点到反射界面任意点的初至旅行时，将两者相加，即可得到总旅行时与界面水平坐标关系曲线。由Fermat原理可知，该曲线上的极值点相对应的时间为反射旅行时，相对应的水平坐标值为反射点位置。本方法不但可计算出任意检波点能接收到的所有的反射液的旅行时及射线路径，而且具有快速、准确、适应复杂构造模型的优点。

基于MTSAT卫星的我国东部沿海雾区的自动识别

本文综合运用可见光反射率阈值法，3X3像元空间一致性检测法，红外亮温闽值法及双通道差值法，建立全天候海雾遥感监测算法，并利用MTSAT卫星资料，对2006年4～5月间我国东部沿海海雾进行个例监测试验，并进行卫星图象的目视真实性检验．监测结果表明，该方法能较好地实现云雾自动分离．在夜间，能有效分离低层云雾和晴空像元；当出现逆温雾时，雾仍可以被有效地判识出来．

FDTD中的一种新截断边界-STWBC

本文提出了一种新的边界条件 :驻波 -行波边界条件 (STWBC) .这种边界条件是在计算域外附加理想导电 (磁 )壁进行截断 ,运用反射原理 ,将边界处的驻波转化为行波 ,保持计算域内的行波状态 ,在有限空间内有效模拟出无限大的电磁散射空间 .文中给出了该边界条件在FDTD中的差分迭代式 ,以及二维数值实验结果 ,并与PML边界和单向波边界进行了比较 .由于该边界比单向波边界所需计算空间小 ,数值稳定性好 ,同时不象PML边界 ,需要进行场量分离和附加额外的吸收层 。