Terahertz Spectroscopic Analysis of Lactose in Infant Formula: Implications for Detection and Quantification.

Lactose plays a significant role in daily lives as a constituent of various food and pharmaceutical products. Yet, lactose intolerance conditions demand low-lactose and lactose-free products in the market. These increasing nutritional claims and labels on food products entail simple and reliable methods of analysis that can be used for meeting quality standards, nutritional claims and legal requirements. In this study, terahertz time-domain spectroscopy (THz-TDS) was employed to analyse α-lactose monohydrate qualitatively and quantitatively in food products. Both absorption spectra and absorption coefficient spectra were investigated for their prediction performance. Regression models for lactose quantification using peak area and height of the absorption peaks 0.53 and 1.37 THz were developed and assessed in infant formula samples. Satisfactory prediction results were achieved in ideal conditions with pure standards, but not in all predictions of infant formula samples. Reasons and further implications are discussed.

Influence of swift heavy ion irradiation on the photoluminescence of Si-nanoparticles and defects in SiO2.

The influence of swift heavy ion (SHI) irradiation on the photoluminescence (PL) of silicon nanoparticles (SiNPs) and defects in SiO2-film is investigated. SiNPs were formed by implantation of 70 keV Si+ and subsequent thermal annealing to produce optically active SiNPs and to remove implantation-induced defects. Seven different ion species with energy between 3-36 MeV and fluence from 1011-1014 cm-2 were employed for irradiation of the implanted samples prior to the thermal annealing. Induced changes in defect and SiNP PL were characterized and correlated with the specific energy loss of the employed SHIs. We find that SHI irradiation, performed before the thermal annealing process, affects both defect and SiNP PL. The change of defect and SiNP PL due to SHI irradiation is found to show a threshold-like behaviour with respect to the electronic stopping power, where a decrease in defect PL and an anticorrelated increase in SiNP PL after the subsequent thermal annealing are observed for electronic stopping exceeding 3-5 keV nm-1. PL intensities are also compared as a function of total energy deposition and nuclear energy loss. The observed effects can be explained by ion track formation as well as a different type of annealing mechanisms active for SHI irradiation compared to the thermal annealing.