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Oxygen and water vapor content, in the lungs of a 3D‐printed phantom model based on CT‐images of a preterm infant, is evaluated using Tunable Diode Laser Absorption Spectroscopy (TDLAS) in Gas in Scattering Media Absorption Spectroscopy (GASMAS), that is, the TDLAS‐GASMAS technique. Oxygen gas is detected through an absorption line near 764 nm and water vapor through an absorption line near 820 nm. A model with a lung containing interior structure is compared to a model with a hollow lung. Compared to the model with the hollow lung, both the mean absorption path length and the transmitted intensity are found to be lower for the model with the structured lung. A new approach, where laser light is delivered internally into the model through an optical fiber, is compared to dermal light administration, that is, illumination onto the skin, for the model with structure inside the lung. The internal light administration generally resulted in larger gas absorption, and higher signal‐to‐noise ratios, compared to the dermal light administration. The results from the phantom measurements show great promise for the internal illumination approach and a natural next step would be to investigate it further in clinical studies. [ABSTRACT FROM AUTHOR]

Currently, there is a need for new technology for in-line or fast at-line assessment of solid material porosity. One specific gap is a fast technology to be used in connection to roller compaction (RC) manufacturing, where the porosity of the RC ribbons is critical to the manufacturing of tablets of the right tensile strength and disintegration properties. In this paper, the development of an at-line technology for fast, non-destructive assessment of porosity of RC ribbons is reported. The technology is based on a diode laser spectroscopic technique called Gas in scattering media absorption spectroscopy (GASMAS). GASMAS measures the sample voids by laser light, giving the distance through air. The total distance the light travels is measured using time-of-flight spectroscopy (TOFS). The ratio of these measures gives an "optical porosity", which through theory relates to the porosity of the sample. We present a description of the technology, evaluations of measurement robustness and results from an experimental design where roller compactor, roll force, roll gap and formulation were varied. It is concluded that the data from two different pharmaceutical formulations is supported by the same calibration curve, which indicates that optical porosimetry is a general technique for pharmaceutical materials that does not require frequent calibrations. [ABSTRACT FROM AUTHOR]