Frozen section analysis is a frequently used method for examination of tissue samples, especially for tumour detection. In the majority of cases, the aim is to identify characteristic tissue morphologies or tumour margins. Depending on the type of tissue, a high number of misdiagnoses are associated with this process. In this work, a fast spectroscopic measurement device and workflow was developed that significantly improves the speed of whole frozen tissue section analyses and provides sufficient information to visualize tissue structures and tumour margins, dependent on their lipid and protein molecular vibrations. That optical and non-destructive method is based on selected wavenumbers in the mid-infrared (MIR) range. We present a measuring system that substantially outperforms a commercially available Fourier Transform Infrared (FT-IR) Imaging system, since it enables acquisition of reduced spectral information at a scan field of 1 cm2 in 3 s, with a spatial resolution of 20 µm. This allows fast visualization of segmented structure areas with little computational effort. For the first time, this multiphotometric MIR system is applied to biomedical tissue sections. We are referencing our novel MIR scanner on cryopreserved murine sagittal and coronal brain sections, especially focusing on the hippocampus, and show its usability for rapid identification of primary hepatocellular carcinoma (HCC) in mouse liver.
In this study, we present an efficient and innovative method to visualize absorption differences in the mid-infrared range with spatial resolution using laser technology. We focus on only two lasers with wavelengths between 3.4 μm and 3.6 μm and a spatial resolution of 20 μm and thus achieve a scanning speed up to 300 kS/s for fast image generation. In this article, we focus especially on the detection of C–H bands in this region of the absorption spectrum. Concealed structures are examined by calculating the measured structures with both wavelengths. In our results, we demonstrate exemplary measurements on 130-μm-thick polyvinyl chloride layers. In turn, these structures are suitable for further processing in rapid quantitative quality control.
In dieser Arbeit wird die Möglichkeit aufgezeigt, mithilfe einer sehr empfindlichen Einzel-Photonenmesstechnik Streulicht von Partikeln zu messen, das durch den Einsatz von Lasern mit extrem geringen Laserintensitäten erzeugt wurde. Die entstehenden Vorteile für nach diesem Prinzip zu bauende Geräte liegen im Bereich Explosionsschutz, Vermeidung von Produktschädigungen und Arbeitssicherheit. Es werden Messaufbauten zum Vermessen von Suspensionen und Aerosolen beschrieben. Laserleistungen kleiner 5 mW werden eingesetzt. Die Messungen beginnen ab einer Partikelgröße von 200 nm und werden in einer 90°-Anordnung als worst case durchgeführt, da bei diesem Winkel ein Minimum an Streuung vorliegt.This work shows the possibility to measure scattered light from particles, which are exposed to miniscule laser intensities, with the help of a very sensitive single-photon measurement technique. The advantages for subsequently designed sensors can be found in explosive prevention, avoiding product damage and improved user safety. Measurement systems to examine suspensions and aerosols are described. Laser output is less than 5 mW. The measurements start at 200 nm particle diameter and are carried out in a 90°arrangement as a worst-case scenario for scattering intensities.
In the presented investigation, the chemical composition of malt during roasting is estimated using diffuse reflectance mid-infrared fourier transform (DRIFT-MIR) spectroscopy and multiple linear regressions. Accordingly, the corresponding test setup is presented and evaluated. A total number of sixty-five stop roasting, having temperature range from 140 to 220ºC, and one unroasted sample of 1500 g Avalon malt are performed in an eddy current roaster. Roasted and unroasted malt samples are milled and then analysed. Additionally, analytical standard reference methods are performed for colour, spectral tristimulus L*a*b* -values, colour difference (E), iron-content, quantitative radical generation and the formation of specific intermediates, such as 5-(hydroxymethyl) furfural (HMF) as well as 3-deoxy-hexosulose (3-DH) and end products of Maillard reaction on all sixty-six samples. Multiple linear regression models were used to predict analysed references based on mid-infrared data, modified with spectral pre-processing for better prediction performance. The obtained results indicate that DRIFT-MIR spectrometry, combined with pre-processing and selection of evaluated wave number areas, is a useful analytical tool for the measurement of quality attributes of malt and therefore, shows potential for application in quality and process control.
The industrial particle sensor market lacks simple, easy to use, low cost yet robust, safe and fast response solutions. Towards development of such a sensor, for in-line use in micro channels under continuous flow conditions, this work introduces static light scattering (SLS) determination of particle diameter using a laser with an emission power of less than 5 µW together with sensitive detectors with detection times of 1 ms. The measurements for the feasibility studies are made in an angular range between 20° and 160° in 2° increments. We focus on the range between 300 and 1000 nm, for applications in the production of paints, colors, pigments and crystallites. Due to the fast response time, reaction characteristics in microchannel designs for precipitation and crystallization processes can be studied. A novel method for particle diameter characterization is developed using the positions of maxima and minima and slope distribution. The novel algorithm to classify particle diameter is especially developed to be independent of dispersed phase concentration or concentration fluctuations like product flares or signal instability. Measurement signals are post processed and particle diameters are validated against Mie light scattering simulations. The design of a low cost instrument for industrial use is proposed.
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