raman laser
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Abstract Intraoperative histopathological examinations are routinely performed to provide neurosurgeons with information about the entity of tumor tissue. Here, we quantified the neuropathological interpretability of stimulated Raman histology (SRH) acquired using a Raman laser imaging system in a routine clinical setting without any specialized training or prior experience. Stimulated Raman scattering microscopy was performed on 117 samples of pathological tissue from 73 cases of brain and spine tumor surgeries. A board-certified neuropathologist — novice in the interpretation of SRH — assessed image quality by scoring subjective tumor infiltration and stated a diagnosis based on the SRH images. The diagnostic accuracy was determined by comparison to frozen hematoxylin–eosin (H&E)-stained sections and the ground truth defined as the definitive neuropathological diagnosis. The overall SRH imaging quality was rated high with the detection of tumor cells classified as inconclusive in only 4.2% of all images. The accuracy of neuropathological diagnosis based on SRH images was 87.7% and was non-inferior to the current standard of fast frozen H&E-stained sections (87.3 vs. 88.9%, p = 0.783). We found a substantial diagnostic correlation between SRH-based neuropathological diagnosis and H&E-stained frozen sections (κ = 0.8). The interpretability of intraoperative SRH imaging was demonstrated to be equivalent to the current standard method of H&E-stained frozen sections. Further research using this label-free innovative alternative vs. conventional staining is required to determine to which extent SRH-based intraoperative decision-making can be streamlined in order to facilitate the advancement of surgical neurooncology.

Adrenaline (Adr) reacts with chlorides of Y3+, Ce3+, Nd3+ and Sm3+ in methanol at 60 °C to yield metal ion adducts of definite composition. These compounds are characterized by elemental analyses, molar conductivity, UV-Vis., 1H–NMR, Raman laser, scanning electron microscopy, energy-dispersive X-ray spectroscopy (EDX), and mid infrared spectral measurement investigations. The adducts are found to have the formulae [Y2(Adr)2(H2O)8]Cl3.8H2O, [Ce(Adr)2(H2O)2]Cl3.10H2O, [Nd(Adr)2(H2O)2]Cl3.6H2O, and [Sm(Adr)2(H2O)2]Cl3.12H2O, respectively. The two phenolic groups of the catechol moiety are linked to central metal ions based on the infrared and Raman laser spectra. The new compounds were tested against five gram-positive and two-gram negative bacteria, in addition to two Aspergillus strains. Metal adducts were shown to have stronger antibacterial and antifungal properties than free adrenaline compounds.

This paper presents a KGW Raman laser with an external-cavity configuration in the 2 μm region. The Raman laser is pumped by unique, electro-optic, actively Q-switched Tm:Yap laser, emitting at 1935 nm. The electro-optic modulation is based on a KLTN crystal, enabling the use of a short crystal length, with a relatively low driving voltage. Due to the KGW bi-axial properties, the Raman laser is able to lase separately at two different output wavelengths, 2273 and 2344 nm. The output energies and pulse durations for these two lines are 0.42 mJ/pulse at 18.2 ns, and 0.416 mJ/pulse at 14.7 ns, respectively. This is the first implementation of a KGW crystal pumped by an electro-optic active Q-switched Tm:Yap laser in the SWIR spectral range.