A comparison between optical properties of TiO2 nanowires obtained by EMA method and experiment

Optical properties of TiO₂ nanowires, synthesized by two-step thermal evaporation process, have been studied experimentally and theoretically. Based on the theoretical method optical constants of nanowires have been calculated with the use of the effective medium approximation (EMA). As evidenced by X-ray diffraction patterns our synthesized nanowires, whose diameters and lengths were within the ranges of 50-90 nm and 500-1500 nm, respectively, were found to be crystalline rutile TiO₂ with the major refraction being along the (1 1 0) direction. The experimental data of the reflectance of TiO₂ nanowires has been obtained using spectrometer in wavelength 250-800 nm, and then, compared with the spectrum of reflectance predicted by the EMA theoretical model. Our measured experimental optical data has been found to be in good accord with our predicted results spectrum with the use of the EMA modeling; this agreement indicates that our estimation of the volume fraction from atomic force microscopy (AFM) data was accurate.     

不同的光透明剂对在体人皮肤组织光学透明的反射光谱研究

研究了经三种不同类型的透明剂处理后的在体人皮组织在波长为400～1 000 nm范围内随时间变化反射光谱特性的变化及各组于580 nm处分别在0～60 min时间段各组反射光谱的改变程度.实验采用USB-4000光纤光谱仪分别获取经丙三醇、葡萄糖及丙二醇处理在体人皮肤组织前后的在0,10,20,30,40,50和60 ...     

An automatic optosensing device for the simultaneous determination of resveratrol and piceid in wines

Despite the increasing number of usage of molecularly imprinted polymers (MIPs) in optical sensor application, the correlation between the analytical signals and the binding isotherms has yet to be fully understood. This work investigates the relationship between the signals generated from MIPs sensors to its respective binding affinity variables generated using binding isotherm models. Two different systems based on the imprinting of metal ion and organic compound have been selected for the study, which employed reflectance and fluorescence sensing schemes, respectively. Batch binding analysis using the standard binding isotherm models was employed to evaluate the affinity of the binding sites. Evaluation using the discrete bi-Langmuir isotherm model found both the MIPs studied have generally two classes of binding sites that was of low and high affinities, while the continuous Freundlich isotherm model has successfully generated a distribution of affinities within the investigated analytical window. When the MIPs were incorporated as sensing receptors, the changes in the analytical signal due to different analyte concentrations were found to have direct correlation with the binding isotherm variables. Further data analyses based on this observation have generated robust models representing the analytical performance of the optical sensors. The best constructed model describing the sensing trend for each of the sensor has been tested and demonstrated to give accurate prediction of concentration for a series of spiked analytes.     

The Omegahat Environment: New Possibilities for Statistical Computing

Abstract

Statistical environments such as S, R, XLisp-Stat, and others have had a dramatic effect on the way we, statistics practitioners, think about data and statistical methodology. However, the possibilities and challenges introduced by recent technological developments and the general ways we use computing conflict with the computational model of these systems. This article explores some of these challenges and identifies the need to support easy integration of functionality from other domains, and to export statistical methodology to other audiences and applications, both statically and dynamically. Existing systems can be improved in these domains with some already implemented extensions (see Section 5). However, the development of a new environment and computational model that exploits modern tools designed to handle many general aspects of these challenges appears more promising as a long-term approach. We present the architecture for such a new model named Omegahat. It lends itself to entirely new statistical computing paradigms. It is highly extensible at both the user and programmer level, and also encourages the development of new environments for different user groups. The Omegahat interactive language offers a continuity between the different programming tasks and levels via optional type checking and seamless access between the interpreted user language and the implementation language, Java. Parallel and distributed computing, network and database access, interactive graphics, and many other aspects of statistical computing are directly accessible to the user as a consequence of this seamless access. We describe the benefits of using Java as the implementation language for the environment and several innovative features of the user-level language which promise to assist development of software that can be used in many contexts. We also outline how this architecture can be integrated with existing environments such as R and S.

The ideas are drawn from work within the Omega Project for Statistical Computing. The project provides open-source software for researching and developing next generation statistical computing tools.     

Effect of metamaterial layer on optical surface plasmon resonance sensor

In this paper an optical surface plasmon resonance (SPR) sensor with metamaterial for four and five layered structure is studied. The numerical results presented in this paper leads to a significant properties of metamaterials in sensing field. Computed results of SPR sensors using metamaterial are compared with conventional optical SPR sensors for four and five layered structure. It is seen that wider dynamic range or effective range of measurable refractive index increases when metamaterial layer is used. It is also verified that SPR sensor with metamaterial layer can dramatically enhance the resolution and reduce the reflectivity compared with conventional SPR. Validity of the magnetic field results is proved on the basis of smooth match of the fields in the different layers of the proposed optical SPR sensor.     

Ultraviolet Spectroscopic Study of the Cellulose Functionalization with Silanes

The reaction of a cellulosic material (Whatman no. 42 filter paper) with two silanes was studied by Diffuse Reflectance Ultraviolet-Visible Spectroscopy and Diffuse Reflectance Fourier Transform Infrared Spectroscopy. The silanes were 3-aminopropyltriethoxysilane (APS) and methyltrimethoxysilane (MS), a silane with a non-reactive organofunctional group. The use of organic peroxides was required in order to achieve an efficient cellulose modification with the silanes. The Diffuse Reflectance UV-VIS Spectroscopy can provide valuable information about the mechanism of the reactions between silanes and cellulose. The reaction between APS and cellulose involves not only the silanol groups of the silane, but also the amino groups. The spectra of APS-trealed celluloses show an absorption band at 325 nm. This band was assigned to imines produced in the reaction of the amino groups of APS with the cellulose. This absorption band increased when APS-treated cellulose was cured at 120°C. The amino groups attached to the cellulose dissappeared in this process     

Diffuse Reflectance Spectra of Rare Earth Benzoylacetonates in Ultraviolet region

Rare earth β-diketonates are promising laser materials. Their solid state spectra is expected to give their spectral characteristics. The diffuse reflectance spectra of some rare earth β-diketonates and esters in ultraviolet region have been reported recently by the authors¹. The ultraviolet absorption spectra of transition metal chelates have also been reported^2,3 recently. The spectra of the non-transition metal ion chelates usually consist⁴ only of the metal charge transfer and ligand intramolecular transitions. The ligand transitions in all the cases are characteristic of the coordinated ligand. The spectrum of the ligand, however, helps in assigning the transitions of the co-ordinated ligand. A comparison of the spectrum of ligands and their rare earth complexes^1,5,6 shows that on complexation no new bands appear in ultraviolet suggesting that unlike transition metal β-diketonates^2,3, charge transfer bands do not appear in the present case. The ligand intramolecular transitions are expected mainly due to the carbonyl group.     

Double-dielectric-mirror InGaN/GaN microcavities formed using selective removal of an AlInN layer

We describe the fabrication and optical properties of a 3λ/2 InGaN/GaN-based microcavity using “upper” and “lower” silica/zirconia mirrors. The fabrication of this structure involved selective removal of an AlInN layer following multistep thinning of a free-standing GaN substrate. Photoluminescence spectra show a narrowing of the excitonic emission from InGaN/GaN quantum wells in the microcavity, giving a cavity quality factor Q exceeding 400.     

Determination of optical constants of silicon photodiode from reflectivity measurements at normal incidence of light

The reflectance of single crystal silicon was carried out at normal angle of incidence in the region from 1 to 5 eV. From these reflectance data, using Kramer–Kronig relations the phase angles between electric fields of incident and reflected waves were calculated. Using the phase angles and Fresnel reflectivity equations, optical constants (n+ik, α, ε₁−iε₂,) of silicon were determined.     

紫外分光光度计反射光谱法研究

在紫外分光光度计上添置一个自制反射光谱法样品架，利用反射光谱附件进行各种固体粉末样品测定。将样品粉末置于不锈钢薄板的圆孔槽内，加盖一决石英片。将制得的样品架置于反射光谱光路中进行光谱测定。试验结果表明，该方法简便快速，并可回收测试样品，对于昂贵样品更为适宜。