Infrared (IR) imaging spectroscopy of human liver tissue slices has been used to identify and characterize liver metastasis of colorectal origin which was surgically removed from a consenting patient and frozen without formalin fixation or dehydration procedures, so that lipids and water remain in the tissues. First, a k-means clustering analysis, using metrics from the IR spectra, identified groups within the image. The groups were identified as tumor or nontumor regions by comparing to an H and E stain of the same sample after IR imaging. Then, calibrant IR spectra of protein, several fats, glycogen, and polyvinyl alcohol were isolated by differencing spectra from different regions or groups in the image space. Finally, inner products (or scores) of the IR spectra at each pixel in the image with each of the various calibrants were calculated showing how the calibrant molecules vary in tumor and nontumor regions. In this particular case, glycogen and protein changes enable separation of tumor and nontumor regions as shown with a contour plot of the glycogen scores versus the protein scores.
Infrared (IR) imaging spectroscopy of human liver tissue slices has been used to identify and characterize a liver metastasis of breast origin (mucinous carcinoma) which was surgically removed from a consenting patient and frozen without formalin fixation or dehydration procedures, so that lipids and water remain in the tissues. Previously, a set of IR metrics was determined for tumors in fixation-free liver tissues facilitating a k-means cluster analysis differentiating tumor from nontumor. Different and more in depth aspects of these results are examined in this work including three metric color imaging, differencing for lipid identification, and a new technique to simultaneously fit band lineshapes and their 2nd derivatives in order to better characterize protein changes.
The adsorption of organics from the gas phase to solid and liquid surfaces is of great interest in the environment. In this study, the surface vibrational spectra of piperidine at the air/liquid interface, air/alumina (a-Al2O3, corundum) (0001) interface and air/a-alumina powder interface were obtained by using vibrational broad bandwidth sum frequency generation (SFG) spectroscopy. The interfacial vibrational signatures in the C-H stretching region of piperidine at the air/liquid and air/solid interfaces are shown to be sensitive spectroscopic-probes revealing the dominating interfacial species. Results indicated that the interfacial species at the air/water interface is mainly hydrogen-bonded piperidine, the interfacial species at the air/alumina (0001) interface is mainly protonated piperidine (piperidium) and the interfacial species at the air/alumina powder interface is mainly liquid-like piperidine.