Tomoya Murakami

Simulation study of in vitro glucose measurement by NIR spectroscopy and a method of error reduction

The effects of some important factors on the blood glucose measurements by NIR spectroscopy are investigated by numerical simulation, and a method is proposed to significantly reduce the prediction errors induced by these effects. The changes in the absorbance spectra with the changes in the glucose concentration, temperature and scattering characteristics of background tissue are obtained by a Monte Carlo simulation of light propagation for the wavelength range from 1200 nm to 1800 nm. The glucose concentration is predicted by applying a multivariate analysis to the numerically simulated spectra. This process estimates the errors in the prediction of the glucose concentration induced by the temperature and scattering changes. It has been found that only 1 C change in the temperature or only 1% change in the scattering coefficient induces about 500 mg dl(-1) or 300 mg dl(-1) errors, respectively, in the prediction of the glucose concentration. These errors can be significantly reduced to less than 20 mg dl(-1) of the glucose concentration by incorporating the effects of the temperature and scattering characteristics on the spectra to the multivariate analysis.

Morphology Evolution of Zinc‐Iron Binary Alloys Electrodeposited with Copper Additive

Zinc-iron electrodeposits have widely been adopted for surface treatment of automobile body steel sheet for corrosion resistance. Copper additive enhances dendrite formation of hexagonal columnar crystals of the zinc-iron electrodeposit. With 100 ppm of copper, these crystals show fine steps on (10 {center_dot} 0){eta} surfaces. With 150 ppm, the copper enhances nucleation on one of an apex on (00{center_dot}1){eta} of these crystals. With 300 ppm, the nucleation increases and fine platelet crystals precipitate preferentially at this apex. With further increase of copper to 1,000 ppm, the deposit becomes dendrite crystals and this apex becomes the growing tip of the dendrite.

Monte Carlo simulation of NIR spectrum changes induced by variations of glucose concentration

We have analyzed the light propagation in tissue simulating media by a Monte Carlo method, using the estimated changes in the optical properties caused by variation of glucose concentration and temperature of the media. Using the calculated data, we have predicted the changes in the absorbance spectra caused by the change in glucose concentration in the absorbing and scattering medium. The predicted spectra have agreed very well with those obtained by the experiments. We have also studied the effects of the varying scattering coefficient on the spectra, and found that the changes in the absolute value and the wavelength dependency of the scattering coefficient are closely related to the changes in the observed spectra. In addition, we have calculated the changes in the absorbance spectra, when the glucose concentration and the temperature of glucose solution vary simultaneously. Using the multivariate analysis, we have extracted the glucose concentration accurately from the calculated absorbance spectra.