In 1963 Umberger and Fiorese (1) introduced a colorimetric method for HA,1 based on the color reaction of HA, dissolved in anhydrous pyridine, with BSC. Therefore, for applying their method to determine HA in urine, HA must first be extracted from the urine. We found that HA dissolved in water-pyridine (1:1, by vol) produces a red-orange color when BSC is added at room temperature. The absorpti...

The large blood vessels would act as a heat sink and hence plays a significant role during photo-thermal therapy. Gold nanoshell was considered as an high heat absorbing agent in photo-thermal heating to reduce the cooling effect of large blood vessels. In this paper, the thermal history of tissue embedded with large blood vessels during photo-thermal heating were calculated using finite elemen...

A rapid, easy, and simple spectrophotometric method was developed for the estimation of total alkaloids precipitated by Dragendorff's reagent (DR) in plant materials. It is based on the formation of yellow bismuth complex in nitric acid medium with thiourea. The yellow-colored complex formed obeys Lambert-Beer's law in the concentration range of 0.06-50 microg/mL with lambdamax at 435 nm. Using...

In this paper, a textile-based sensing principle for long term photopletysmography (PPG) monitoring is presented. Optical fibers were embroidered into textiles such that out-coupling and in-coupling of light was possible. The "light-in light-out" properties of the textile enabled the spectroscopic characterization of human tissue. For the optimization of the textile sensor, three different carr...

This paper discusses the accuracy of the optical determination of the oxygenated and deoxygenated hemoglobin content of human skin under the influence of a melanin layer for a multi-wavelengths imager. The relation between the nonlinear results by Monte Carlo simulation (MCS) and the modified Lambert Beer's law (MLB) is also clarified, emphasizing the importance of the absolute values of skin p...

Qualitative and quantitative determination of chemicals especially that deal with drugs and pharmaceuticals can be considered as important issues in scientific research to insure human safety and security. With this direction of scientific research, folic acid had been determined qualitatively and quantitatively through applying FTIR technique. By applying a weight range of the pure compound, t...

We have studied the effect on 2 nd harmonic wavelength modulation spectroscopy of the use of integrating spheres as multipass gas cells. The gas lineshape becomes distorted at high concentrations, as a consequence of the exponential pathlength distribution of the sphere, introducing nonlinearity beyond that expected from the Beer-Lambert law. We have modelled this numerically for methane absorp...

We study the problem of heating a one-dimensional approximation to a slb-sided moist foodstuff in a microwave oven, allowing for a phase change and drying. We initially investigate the accuracy of the Lambert law of exponential decay of the applied electric field into the foodstuff and derive an approximation for the field comprising the exponential decay term and an oscillatory component. We t...