Refractometry

A nonlinear image technique for characterization of the optical nonlinearities is used to investigate the solid semiconductor ZnSe at 600 nm. The method based on a 4f nonlinear image technique with a phase object is used to obtain the diffraction pattern of the nonlinear filter in solid ZnSe located at the Fourier plane by a CCD camera. The nonlinear absorption coefficient and nonlinear refraction index were both obtained by fitting the nonlinear image. Good agreement between the experiment data and the simulated result are obtained indicating a sensitive and powerful method for nonlinear optical measurements.

A novel drug-delivery system was developed by loading the anticancer drug, mitomycin C (MC) into an oil/water system with the aim of investigation by electrochemical sensing the interaction between the drug and DNA in microemulsion phase. The physical and physicochemical properties (droplet size, pH, viscosity, conductivity and refractive index) of this microemulsion were examined. The electrochemical detection of the interaction between MC and double-stranded DNA (dsDNA) in microemulsion phase was performed by using differential pulse voltammetry (DPV) in combination with a disposable sensor, pencil graphite electrode (PGE). The magnitude of guanine oxidation signal was monitored before and after interaction between MC and dsDNA. The effect of different experimental parameters, such as MC concentration, MC interaction time with dsDNA, and dsDNA concentration were also studied to find the optimum analytical performance based on electrochemical detection of this interaction in microe...

We demonstrate a first simultaneous measurement of both the refractive index and the attenuation coefficient (defined as the sum of the scattering and absorption coefficients) of highly turbid milk and milk-cream mixtures. We achieve this by observing the real-time reflectance profile of a divergent laser beam made incident on the surface of the milk sample. The experiments were carried out on commercial milk samples with fat volume concentrations of 0.5 or less, 1.6, and 3.3%, and on milk-cream mixtures with fat volume concentrations of 10 and 33.3%, without any dilutions of these samples. We find that the reflectance data are well described, for the first time without any empirical fit-parameters, by Fresnel theory that correctly includes the effect of angle-dependent penetration into the turbid medium on the total internally reflected signal. Therefore, our method provides the most accurate determination to date of the refractive index and attenuation coefficient of milk and milk...

The arrangement of binary subwavelength structures is a promising alternative to the conventional multiheight level technique to generate computer generated holograms (CGHs). However, the current heuristic design approach leads to a slight mismatch between the target signal and experimental data. To evaluate this deviation, a diffractive beam splitter design is investigated rigorously using a finite-difference time-domain (FDTD) method. Since the use of a rigorous Maxwell-equation solver like FDTD requires a massive computational effort, an alternative scalar approach, a fast Fourier transform beam propagation method (FFT-BPM), is investigated with a substantial higher computing speed, showing still a good agreement with the FDTD simulation and experimental data. Therefore, an implementation of this scalar approach into the CGH design process offers the possibility to significantly increase the accuracy.

Gel filtration chromatography using a TSKgel G2000 SW column coupled with differential refractive index detection was used to analyse five grades of polyvinyl alcohol. Limits of detection and quantification for the assay were 0.14 mg mL -1, 0.47 mg mL -1 respectively. The inter and intra-day co-efficient of variance were both pn=5) between the calibration curves across the five grades

We extend the design of radially symmetric three-dimensional invisibility cloaks through transformation optics to cloaks with a surface of revolution. We derive the expression of the transformation matrix and show that one of its eigenvalues vanishes on the inner boundary of the cloaks, while the other two remain strictly positive and bounded. The validity of our approach is confirmed by finite edge-elements computations for a non-convex cloak of varying thickness.

PURPOSE. An association between tonic accommodation, the resting accommodative position of the eye in the absence of a visually compelling stimulus, and refractive error has been reported in adults and children. In general, myopes have the lowest (or least myopic) levels of tonic accommodation. The purpose in assessing tonic accommodation was to evaluate it as a predictor of onset of

The aim of this study was to estimate the agreement between an autorefractor (Nidek ARK 700A, Gamagori, Japan) and retinoscopy with subjective refraction. Measurements of autorefraction obtained with the ARK700A and retinoscopy were performed on 192 right eyes from 192 healthy young adults and compared with subjective refraction. These measurements were performed without cycloplegia. The age range was 18 to 34 years, with a mean value of 21.6 years and an SD of 2.66 years. A comparison of the autorefractor and subjective refraction results shows that (1) for the mean spherical equivalent (M), the autorefractor yields more negative values (-0.44 +/- 0.54 D; p = 0.000); (2) for the Jackson cross-cylinder at axis 0 degrees (J0), the autorefractor yields more positive values than the subjective ones (0.05 +/- 0.13 D; p = 0.000); and (3) for the Jackson cross-cylinder at axis 45 degrees (J45), the autorefractor results are more negative (-0.02 +/- 0.09 D; p = 0.019). The differences foun...

Size exclusion chromatography (SEC) is a historical technique widely employed for the detailed characterization of therapeutic proteins and can be considered as a reference and powerful technique for the qualitative and quantitative evaluation of aggregates. The main advantage of this approach is the mild mobile phase conditions that permit the characterization of proteins with minimal impact on the conformational structure and local environment. Despite the fact that the chromatographic behavior and peak shape are hardly predictable in SEC, some generic rules can be applied for SEC method development, which are described in this review. During recent years, some improvements were introduced to conventional SEC that will also be discussed. Of these new SEC characteristics, we discuss (i) the commercialization of shorter and narrower columns packed with reduced particle sizes allowing an improvement in the resolution and throughput; (ii) the possibility of combining SEC with various ...